document_title: Sound localization

question_text: when will a sound be in the cone of confusion

root

text: Sound localization

text: How sound reaches the brain[edit]

text: Sound is the perceptual result of mechanical vibrations traveling through a medium such as air or water. Through the mechanisms of compression and rarefaction, sound waves travel through the air, bounce off the pinna and concha of the exterior ear, and enter the ear canal. The sound waves vibrate the tympanic membrane (ear drum), causing the three bones of the middle ear to vibrate, which then sends the energy through the oval window and into the cochlea where it is changed into a chemical signal by hair cells in the organ of corti, which synapse onto spiral ganglion fibers that travel through the cochlear nerve into the brain.

tag: p

text: Neural interactions[edit]

text: In vertebrates, inter-aural time differences are known to be calculated in the superior olivary nucleus of the brainstem. According to Jeffress,[1] this calculation relies on delay lines: neurons in the superior olive which accept innervation from each ear with different connecting axon lengths. Some cells are more directly connected to one ear than the other, thus they are specific for a particular inter-aural time difference. This theory is equivalent to the mathematical procedure of cross-correlation. However, because Jeffress' theory is unable to account for the precedence effect, in which only the first of multiple identical sounds is used to determine the sounds' location (thus avoiding confusion caused by echoes), it cannot be entirely used to explain the response. Furthermore, a number of recent physiological observations made in the midbrain and brainstem of small mammals have shed considerable doubt on the validity of Jeffress' original ideas [2]

text: Neurons sensitive to inter-aural level differences (ILDs) are excited by stimulation of one ear and inhibited by stimulation of the other ear, such that the response magnitude of the cell depends on the relative strengths of the two inputs, which in turn, depends on the sound intensities at the ears.

text: In the auditory midbrain nucleus, the inferior colliculus (IC), many ILD sensitive neurons have response functions that decline steeply from maximum to zero spikes as a function of ILD. However, there are also many neurons with much more shallow response functions that do not decline to zero spikes.

text: The cone of confusion[edit]

text: Most mammals are adept at resolving the location of a sound source using interaural time differences and interaural level differences. However, no such time or level differences exist for sounds originating along the circumference of circular conical slices, where the cone's axis lies along the line between the two ears.

text: Consequently, sound waves originating at any point along a given circumference slant height will have ambiguous perceptual coordinates. That is to say, the listener will be incapable of determining whether the sound originated from the back, front, top, bottom or anywhere else along the circumference at the base of a cone at any given distance from the ear. Of course, the importance of these ambiguities are vanishingly small for sound sources very close to or very far away from the subject, but it is these intermediate distances that are most important in terms of fitness.

text: These ambiguities can be removed by tilting the head, which can introduce a shift in both the amplitude and phase of sound waves arriving at each ear. This translates the vertical orientation of the interaural axis horizontally, thereby leveraging the mechanism of localization on the horizontal plane. Moreover, even with no alternation in the angle of the interaural axis (i.e. without tilting one's head) the hearing system can capitalize on interference patterns generated by pinnae, the torso, and even the temporary re-purposing of a hand as extension of the pinna (e.g., cupping one's hand around the ear).

text: As with other sensory stimuli, perceptual disambiguation is also accomplished through integration of multiple sensory inputs, especially visual cues. Having localized a sound within the circumference of a circle at some perceived distance, visual cues serve to fix the location of the sound. Moreover, prior knowledge of the location of the sound generating agent will assist in resolving its current location.

text: Sound localization by the human auditory system[edit]

text: Sound localization is the process of determining the location of a sound source. Objectively speaking, the major goal of sound localization is to simulate a specific sound field, including the acoustic sources, the listener, the media and environments of sound propagation. The brain utilizes subtle differences in intensity, spectral, and timing cues to allow us to localize sound sources.[3][4] In this section, to more deeply understand the human auditory mechanism, we will briefly discuss about human ear localization theory.

text: General Introduction[edit]

text: Localization can be described in terms of three-dimensional position: the azimuth or horizontal angle, the elevation or vertical angle, and the distance (for static sounds) or velocity (for moving sounds).[5]

text: The azimuth of a sound is signaled by the difference in arrival times between the ears, by the relative amplitude of high-frequency sounds (the shadow effect), and by the asymmetrical spectral reflections from various parts of our bodies, including torso, shoulders, and pinnae.[5]

text: The distance cues are the loss of amplitude, the loss of high frequencies, and the ratio of the direct signal to the reverberated signal.[5]

text: Depending on where the source is located, our head acts as a barrier to change the timbre, intensity, and spectral qualities of the sound, helping the brain orient where the sound emanated from.[4] These minute differences between the two ears are known as interaural cues.[4]

text: Lower frequencies, with longer wavelengths, diffract the sound around the head forcing the brain to focus only on the phasing cues from the source.[4]

text: Helmut Haas discovered that we can discern the sound source despite additional reflections at 10 decibels louder than the original wave front, using the earliest arriving wave front.[4] This principle is known as the Haas effect, a specific version of the precedence effect.[4] Haas measured down to even a 1 millisecond difference in timing between the original sound and reflected sound increased the spaciousness, allowing the brain to discern the true location of the original sound. The nervous system combines all early reflections into a single perceptual whole allowing the brain to process multiple different sounds at once.[6] The nervous system will combine reflections that are within about 35 milliseconds of each other and that have a similar intensity.[6]

text: Duplex Theory[edit]

text: To determine the lateral input direction (left, front, right), the auditory system analyzes the following ear signal information:

text: Duplex Theory[edit]

text: In 1907, Lord Rayleigh utilized tuning forks to generate monophonic excitation and studied the lateral sound localization theory on a human head model without auricle. He first presented the interural clue difference based sound localization theory, which is known as Duplex Theory.[7] Human ears are on the different sides of the head, thus they have different coordinates in space. As shown in fig. 2, since the distances between the acoustic source and ears are different, there are time difference and intensity difference between the sound signals of two ears. We call those kinds of differences as Interaural Time Difference (ITD) and Interaural Intensity Difference (IID) respectively.

text: ITD and IID[edit]

text: From fig.2 we can see that no matter for source B1 or source B2, there will be a propagation delay between two ears, which will generate the ITD. Simultaneously, human head and ears may have shadowing effect on high frequency signals, which will generate IID.

text:
Interaural Time Difference (ITD) Sound from the right side reaches the right ear earlier than the left ear. The auditory system evaluates interaural time differences from: (a) Phase delays at low frequencies and (b) group delays at high frequencies.
Massive experiments demonstrate that ITD relates to the signal frequency f. Suppose the angular position of the acoustic source is θ, the head radius is r and the acoustic velocity is c, the function of ITD is given by:[8]

I
T
D
=

{

300
×

r

×
sin

θ

/

c

,

if

f
≤

4000Hz

200
×

r

×
sin

θ

/

c

,

if

f
>

 4000Hz

{\displaystyle ITD={\begin{cases}300\times {\text{r}}\times \sin \theta /{\text{c}},&{\text{if }}f\leq {\text{4000Hz }}\\200\times {\text{r}}\times \sin \theta /{\text{c}},&{\text{if }}f>{\text{ 4000Hz}}\end{cases}}}

. In above closed form, we assumed that the 0 degree is in the right ahead of the head and counter-clockwise is positive.
Interaural Intensity Difference (IID) or Interaural Level Difference (ILD) Sound from the right side has a higher level at the right ear than at the left ear, because the head shadows the left ear. These level differences are highly frequency dependent and they increase with increasing frequency. Massive theoretical researches demonstrate that IID relates to the signal frequency f and the angular position of the acoustic source θ. The function of IID is given by:[8]

I
I
D
=
1.0
+
(
f

/

1000

)

0.8

×
sin

θ

{\displaystyle IID=1.0+(f/1000)^{0.8}\times \sin \theta }

For frequencies below 1000 Hz, mainly ITDs are evaluated (phase delays), for frequencies above 1500 Hz mainly IIDs are evaluated. Between 1000 Hz and 1500 Hz there is a transition zone, where both mechanisms play a role.
Localization accuracy is 1 degree for sources in front of the listener and 15 degrees for sources to the sides. Humans can discern interaural time differences of 10 microseconds or less.[9][10]

text: Evaluation for low frequencies[edit]

text: For frequencies below 800 Hz, the dimensions of the head (ear distance 21.5 cm, corresponding to an interaural time delay of 625 µs) are smaller than the half wavelength of the sound waves. So the auditory system can determine phase delays between both ears without confusion. Interaural level differences are very low in this frequency range, especially below about 200 Hz, so a precise evaluation of the input direction is nearly impossible on the basis of level differences alone. As the frequency drops below 80 Hz it becomes difficult or impossible to use either time difference or level difference to determine a sound's lateral source, because the phase difference between the ears becomes too small for a directional evaluation.[11]

text: Evaluation for high frequencies[edit]

text: For frequencies above 1600 Hz the dimensions of the head are greater than the length of the sound waves. An unambiguous determination of the input direction based on interaural phase alone is not possible at these frequencies. However, the interaural level differences become larger, and these level differences are evaluated by the auditory system. Also, group delays between the ears can be evaluated, and is more pronounced at higher frequencies; that is, if there is a sound onset, the delay of this onset between the ears can be used to determine the input direction of the corresponding sound source. This mechanism becomes especially important in reverberant environments. After a sound onset there is a short time frame where the direct sound reaches the ears, but not yet the reflected sound. The auditory system uses this short time frame for evaluating the sound source direction, and keeps this detected direction as long as reflections and reverberation prevent an unambiguous direction estimation.[12] The mechanisms described above cannot be used to differentiate between a sound source ahead of the hearer or behind the hearer; therefore additional cues have to be evaluated.[13]

text: Pinna Filtering Effect Theory[edit]

text: Motivations[edit]

text: Duplex theory clearly points out that ITD and IID play significant roles in sound localization but they can only deal with lateral localizing problems. For example, based on duplex theory, if two acoustic sources are symmetrically located on the right front and right back of the human head, they will generate equal ITDs and IIDs, which is called as cone model effect. However, human ears can actually distinguish this set of sources. Besides that, in natural sense of hearing, only one ear, which means no ITD or IID, can distinguish the sources with a high accuracy. Due to the disadvantages of duplex theory, researchers proposed the pinna filtering effect theory.[14] The shape of human pinna is very special. It is concave with complex folds and asymmetrical no matter horizontally or vertically. The reflected waves and the direct waves will generate a frequency spectrum on the eardrum, which is related to the acoustic sources. Then auditory nerves localize the sources by this frequency spectrum. Therefore, a corresponding theory was proposed and called as pinna filtering effect theory.[15]

text: Math Model[edit]

text: These spectrum clue generated by pinna filtering effect can be presented as Head-Related Transfer Functions (HRTF). The corresponding time domain expressions are called as Head-Related Impulse Response (HRIR). HRTF is also called as the transfer function from the free field to a specific point in the ear canal. We usually recognize HRTFs as LTI systems:[8]

text:
H

L

=

H

L

(
r
,
θ
,
φ
,
ω
,
α
)
=

P

L

(
r
,
θ
,
φ
,
ω
,
α
)

/

P

0

(
r
,
ω
)

{\displaystyle H_{L}=H_{L}(r,\theta ,\varphi ,\omega ,\alpha )=P_{L}(r,\theta ,\varphi ,\omega ,\alpha )/P_{0}(r,\omega )}

text:
H

R

=

H

R

(
r
,
θ
,
φ
,
ω
,
α
)
=

P

R

(
r
,
θ
,
φ
,
ω
,
α
)

/

P

0

(
r
,
ω
)

{\displaystyle H_{R}=H_{R}(r,\theta ,\varphi ,\omega ,\alpha )=P_{R}(r,\theta ,\varphi ,\omega ,\alpha )/P_{0}(r,\omega )}

,

text:
where L and R represent the left ear and right ear respectively.

P

L

{\displaystyle P_{L}}

 and

P

R

{\displaystyle P_{R}}

 represent the amplitude of sound pressure at entrances of left and right ear canal.

P

0

{\displaystyle P_{0}}

 is the amplitude of sound pressure at the center of the head coordinate when listener does not exist. In general, HRTFs

H

L

{\displaystyle H_{L}}

 and

H

R

{\displaystyle H_{R}}

 are functions of source angular position

θ

{\displaystyle \theta }

, elevation angle

φ

{\displaystyle \varphi }

, distance between source and center of the head

r

{\displaystyle r}

, the angular velocity

ω

{\displaystyle \omega }

 and the equivalent dimension of the head

α

{\displaystyle \alpha }

.

text: HRTF Database[edit]

text: At present, the main institutes that work on measuring HRTF database includes CIPIC[16] International Lab, MIT Media Lab, The Graduate School in Psychoacoustics at the University of Oldenburg, Neurophysiology Lab in University of Wisconsin-Madison and Ames Lab of NASA. They carefully measures the HRIRs from both humans and animals and share the results on Internet for people who want to study.

text: Other Cues for 3D Space Localization[edit]

text: Monaural cues[edit]

text: The human outer ear, i.e. the structures of the pinna and the external ear canal, form direction-selective filters. Depending on the sound input direction in the median plane, different filter resonances become active. These resonances implant direction-specific patterns into the frequency responses of the ears, which can be evaluated by the auditory system (directional bands) for vertical sound localization. Together with other direction-selective reflections at the head, shoulders and torso, they form the outer ear transfer functions. These patterns in the ear's frequency responses are highly individual, depending on the shape and size of the outer ear. If sound is presented through headphones, and has been recorded via another head with different-shaped outer ear surfaces, the directional patterns differ from the listener's own, and problems will appear when trying to evaluate directions in the median plane with these foreign ears. As a consequence, front–back permutations or inside-the-head-localization can appear when listening to dummy head recordings, or otherwise referred to as binaural recordings. It has been shown that human subjects can monaurally localize high frequency sound but not low frequency sound. Binaural localization, however, was possible with lower frequencies. This is likely due to the pinna being small enough to only interact with sound waves of high frequency.[17] It seems that people can only accurately localize the elevation of sounds that are complex and include frequencies above 7,000 Hz, and a pinna must be present.[18]

text: Dynamic binaural cues[edit]

text: When the head is stationary, the binaural cues for lateral sound localization (interaural time difference and interaural level difference) do not give information about the location of a sound in the median plane. Identical ITDs and ILDs can be produced by sounds at eye level or at any elevation, as long as the lateral direction is constant. However, if the head is rotated, the ITD and ILD change dynamically, and those changes are different for sounds at different elevations. For example, if an eye-level sound source is straight ahead and the head turns to the left, the sound becomes louder (and arrives sooner) at the right ear than at the left. But if the sound source is directly overhead, there will be no change in the ITD and ILD as the head turns. Intermediate elevations will produce intermediate degrees of change, and if the presentation of binaural cues to the two ears during head movement is reversed, the sound will be heard behind the listener.[13][19] Hans Wallach[20] artificially altered a sound’s binaural cues during movements of the head. Although the sound was objectively placed at eye level, the dynamic changes to ITD and ILD as the head rotated were those that would be produced if the sound source had been elevated. In this situation, the sound was heard at the synthesized elevation. The fact that the sound sources objectively remained at eye level prevented monaural cues from specifying the elevation, showing that it was the dynamic change in the binaural cues during head movement that allowed the sound to be correctly localized in the vertical dimension. The head movements need not be actively produced; accurate vertical localization occurred in a similar setup when the head rotation was produced passively, by seating the blindfolded subject in a rotating chair. As long as the dynamic changes in binaural cues accompanied a perceived head rotation, the synthesized elevation was perceived.[13]

text: Distance of the sound source[edit]

text: The human auditory system has only limited possibilities to determine the distance of a sound source. In the close-up-range there are some indications for distance determination, such as extreme level differences (e.g. when whispering into one ear) or specific pinna (the visible part of the ear) resonances in the close-up range.

text: The auditory system uses these clues to estimate the distance to a sound source:

text:
Direct/ Reflection ratio: In enclosed rooms, two types of sound are arriving at a listener: The direct sound arrives at the listener's ears without being reflected at a wall. Reflected sound has been reflected at least one time at a wall before arriving at the listener. The ratio between direct sound and reflected sound can give an indication about the distance of the sound source.
Loudness: Distant sound sources have a lower loudness than close ones. This aspect can be evaluated especially for well-known sound sources.
Sound spectrum : High frequencies are more quickly damped by the air than low frequencies. Therefore, a distant sound source sounds more muffled than a close one, because the high frequencies are attenuated. For sound with a known spectrum (e.g. speech) the distance can be estimated roughly with the help of the perceived sound.
ITDG: The Initial Time Delay Gap describes the time difference between arrival of the direct wave and first strong reflection at the listener. Nearby sources create a relatively large ITDG, with the first reflections having a longer path to take, possibly many times longer. When the source is far away, the direct and the reflected sound waves have similar path lengths.
Movement: Similar to the visual system there is also the phenomenon of motion parallax in acoustical perception. For a moving listener nearby sound sources are passing faster than distant sound sources.
Level Difference: Very close sound sources cause a different level between the ears.

text: Signal processing[edit]

text: Sound processing of the human auditory system is performed in so-called critical bands. The hearing range is segmented into 24 critical bands, each with a width of 1 Bark or 100 Mel. For a directional analysis the signals inside the critical band are analyzed together.

text: The auditory system can extract the sound of a desired sound source out of interfering noise. This allows the listener to concentrate on only one speaker if other speakers are also talking (the cocktail party effect). With the help of the cocktail party effect sound from interfering directions is perceived attenuated compared to the sound from the desired direction. The auditory system can increase the signal-to-noise ratio by up to 15 dB, which means that interfering sound is perceived to be attenuated to half (or less) of its actual loudness.[citation needed]

text: Localization in enclosed rooms[edit]

text: In enclosed rooms not only the direct sound from a sound source is arriving at the listener's ears, but also sound which has been reflected at the walls. The auditory system analyses only the direct sound,[12] which is arriving first, for sound localization, but not the reflected sound, which is arriving later (law of the first wave front). So sound localization remains possible even in an echoic environment. This echo cancellation occurs in the Dorsal Nucleus of the Lateral Lemniscus (DNLL).[citation needed]

text: In order to determine the time periods, where the direct sound prevails and which can be used for directional evaluation, the auditory system analyzes loudness changes in different critical bands and also the stability of the perceived direction. If there is a strong attack of the loudness in several critical bands and if the perceived direction is stable, this attack is in all probability caused by the direct sound of a sound source, which is entering newly or which is changing its signal characteristics. This short time period is used by the auditory system for directional and loudness analysis of this sound. When reflections arrive a little bit later, they do not enhance the loudness inside the critical bands in such a strong way, but the directional cues become unstable, because there is a mix of sound of several reflection directions. As a result, no new directional analysis is triggered by the auditory system.

text: This first detected direction from the direct sound is taken as the found sound source direction, until other strong loudness attacks, combined with stable directional information, indicate that a new directional analysis is possible. (see Franssen effect)

text: Specific techniques with applications[edit]

text: Auditory transmission stereo system[edit]

text: This kind of sound localization technique provides us the real virtual stereo system.[21] It utilizes "smart" manikins, such as KEMAR, to glean signals or use DSP methods to simulate the transmission process from sources to ears. After amplifying, recording and transmitting, the two channels of received signals will be reproduced through earphones or speakers. This localization approach uses electroacoustic methods to obtain the spatial information of the original sound field by transferring the listener's auditory apparatus to the original sound field. The most considerable advantages of it would be that its acoustic images are lively and natural. Also, it only needs two independent transmitted signal to reproduce the acoustic image of a 3D system.

text: 3D para-virtualization stereo system[edit]

text: The representatives of this kind of system are SRS Audio Sandbox, Spatializer Audio Lab and Qsound Qxpander.[21] They use HRTF to simulate the received acoustic signals at the ears from different directions with common binary-channel stereo reproduction. Therefore, they can simulate reflected sound waves and improve subjective sense of space and envelopment. Since they are para-virtualization stereo systems, the major goal of them is to simulate stereo sound information. Traditional stereo systems use sensors that are quite different from human ears. Although those sensors can receive the acoustic information from different directions, they do not have the same frequency response of human auditory system. Therefore, when binary-channel mode is applied, human auditory systems still cannot feel the 3D sound effect field. However, the 3D para-virtualization stereo system overcome such disadvantages. It uses HRTF principles to glean acoustic information from the original sound field then produce a lively 3D sound field through common earphones or speakers.

text: Multichannel stereo virtual reproduction[edit]

text: Since the multichannel stereo systems require lots of reproduction channels, some researchers adopted the HRTF simulation technologies to reduce the number of reproduction channels.[21] They use only two speakers to simulate multiple speakers in a multichannel system. This process is called as virtual reproduction. Essentially, such approach uses both interaural difference principle and pinna filtering effect theory. Unfortunately, this kind of approach cannot perfectly substitute the traditional multichannel stereo system, such as 5.1 surround sound system. That is because when the listening zone is relatively larger, simulation reproduction through HRTFs may cause invert acoustic images at symmetric positions.

text: Animals[edit]

text: Since most animals have two ears, many of the effects of the human auditory system can also be found in other animals. Therefore, interaural time differences (interaural phase differences) and interaural level differences play a role for the hearing of many animals. But the influences on localization of these effects are dependent on head sizes, ear distances, the ear positions and the orientation of the ears.

text: Lateral information (left, ahead, right)[edit]

text: If the ears are located at the side of the head, similar lateral localization cues as for the human auditory system can be used. This means: evaluation of interaural time differences (interaural phase differences) for lower frequencies and evaluation of interaural level differences for higher frequencies. The evaluation of interaural phase differences is useful, as long as it gives unambiguous results. This is the case, as long as ear distance is smaller than half the length (maximal one wavelength) of the sound waves. For animals with a larger head than humans the evaluation range for interaural phase differences is shifted towards lower frequencies, for animals with a smaller head, this range is shifted towards higher frequencies.

text: The lowest frequency which can be localized depends on the ear distance. Animals with a greater ear distance can localize lower frequencies than humans can. For animals with a smaller ear distance the lowest localizable frequency is higher than for humans.

text: If the ears are located at the side of the head, interaural level differences appear for higher frequencies and can be evaluated for localization tasks. For animals with ears at the top of the head, no shadowing by the head will appear and therefore there will be much less interaural level differences, which could be evaluated. Many of these animals can move their ears, and these ear movements can be used as a lateral localization cue.

text: Odontocetes[edit]

text: Dolphins (and other odontocetes) rely on echolocation to aid in detecting, identifying, localizing, and capturing prey. Dolphin sonar signals are well suited for localizing multiple, small targets in a three-dimensional aquatic environment by utilizing highly directional (3 dB beamwidth of about 10 deg), broadband (3 dB bandwidth typically of about 40 kHz; peak frequencies between 40 kHz and 120 kHz), short duration clicks (about 40 μs). Dolphins can localize sounds both passively and actively (echolocation) with a resolution of about 1 deg. Cross-modal matching (between vision and echolocation) suggests dolphins perceive the spatial structure of complex objects interrogated through echolocation, a feat that likely requires spatially resolving individual object features and integration into a holistic representation of object shape. Although dolphins are sensitive to small, binaural intensity and time differences, mounting evidence suggests dolphins employ position-dependent spectral cues derived from well-developed head-related transfer functions, for sound localization in both the horizontal and vertical planes. A very small temporal integration time (264 μs) allows localization of multiple targets at varying distances. Localization adaptations include pronounced asymmetry of the skull, nasal sacks, and specialized lipid structures in the forehead and jaws, as well as acoustically isolated middle and inner ears.

text: In the median plane (front, above, back, below)[edit]

text: For many mammals there are also pronounced structures in the pinna near the entry of the ear canal. As a consequence, direction-dependent resonances can appear, which could be used as an additional localization cue, similar to the localization in the median plane in the human auditory system. There are additional localization cues which are also used by animals.

text: Head tilting[edit]

text: For sound localization in the median plane (elevation of the sound) also two detectors can be used, which are positioned at different heights. In animals, however, rough elevation information is gained simply by tilting the head, provided that the sound lasts long enough to complete the movement. This explains the innate behavior of[vague] cocking the head to one side when trying to localize a sound precisely. To get instantaneous localization in more than two dimensions from time-difference or amplitude-difference cues requires more than two detectors.

text: Localization with coupled ears (flies)[edit]

text: The tiny parasitic fly Ormia ochracea has become a model organism in sound localization experiments because of its unique ear. The animal is too small for the time difference of sound arriving at the two ears to be calculated in the usual way, yet it can determine the direction of sound sources with exquisite precision. The tympanic membranes of opposite ears are directly connected mechanically, allowing resolution of sub-microsecond time differences[22][23] and requiring a new neural coding strategy.[24] Ho[25] showed that the coupled-eardrum system in frogs can produce increased interaural vibration disparities when only small arrival time and sound level differences were available to the animal's head. Efforts to build directional microphones based on the coupled-eardrum structure are underway.

text: Bi-coordinate sound localization (owls)[edit]

text: Most owls are nocturnal or crepuscular birds of prey. Because they hunt at night, they must rely on non-visual senses. Experiments by Roger Payne[26] have shown that owls are sensitive to the sounds made by their prey, not the heat or the smell. In fact, the sound cues are both necessary and sufficient for localization of mice from a distant location where they are perched. For this to work, the owls must be able to accurately localize both the azimuth and the elevation of the sound source.

text: History[edit]

text: The term 'binaural' literally signifies 'to hear with two ears', and was introduced in 1859 to signify the practice of listening to the same sound through both ears, or to two discrete sounds, one through each ear. It was not until 1916 that Carl Stumpf (1848–1936), a German philosopher and psychologist, distinguished between dichotic listening, which refers to the stimulation of each ear with a different stimulus, and diotic listening, the simultaneous stimulation of both ears with the same stimulus.[27]

text: Later, it would become apparent that binaural hearing, whether dichotic or diotic, is the means by which sound localization occurs.[27][28][page needed]

text: Scientific consideration of binaural hearing began before the phenomenon was so named, with speculations published in 1792 by William Charles Wells (1757–1817) based on his research into binocular vision.[29] Giovanni Battista Venturi (1746–1822) conducted and described experiments in which people tried to localize a sound using both ears, or one ear blocked with a finger. This work was not followed up on, and was only recovered after others had worked out how human sound localization works.[27][29] Lord Rayleigh (1842–1919) would do these same experiments and come to the results, without knowing Venturi had first done them, almost seventy-five years later.[29]

text: Charles Wheatstone (1802–1875) did work on optics and color mixing, and also explored hearing. He invented a device he called a "microphone" that involved a metal plate over each ear, each connected to metal rods; he used this device to amplify sound. He also did experiments holding tuning forks to both ears at the same time, or separately, trying to work out how sense of hearing works, that he published in 1827.[29] Ernst Heinrich Weber (1795–1878) and August Seebeck (1805–1849) and William Charles Wells also attempted to compare and contrast what would become known as binaural hearing with the principles of binocular integration generally.[29]

text: Understanding how the differences in sound signals between two ears contributes to auditory processing in such a way as to enable sound localization and direction was considerably advanced after the invention of the stethophone by Somerville Scott Alison in 1859, who coined the term 'binaural'. Alsion based the stethophone on the stethoscope, which had been invented by René Théophile Hyacinthe Laennec (1781–1826); the stethophone had two separate "pickups", allowing the user to hear and compare sounds derived from two discrete locations.[29][29]


document_title: Venture capital

question_text: when did the modern venture capital industry in the usa most likely begin

question_tokens: when did the modern venture capital industry in the usa most likely begin

text: Venture capital

text: History[edit]

text: A venture may be defined as a project prospective converted into a process with an adequate assumed risk and investment. With few exceptions, private equity in the first half of the 20th century was the domain of wealthy individuals and families. The Wallenbergs, Vanderbilts, Whitneys, Rockefellers, and Warburgs were notable investors in private companies in the first half of the century. In 1938, Laurance S. Rockefeller helped finance the creation of both Eastern Air Lines and Douglas Aircraft, and the Rockefeller family had vast holdings in a variety of companies. Eric M. Warburg founded E.M. Warburg & Co. in 1938, which would ultimately become Warburg Pincus, with investments in both leveraged buyouts and venture capital. The Wallenberg family started Investor AB in 1916 in Sweden and were early investors in several Swedish companies such as ABB, Atlas Copco, Ericsson, etc. in the first half of the 20th century.

text: Origins of modern private equity[edit]

text: Before World War II (1939–1945), money orders (originally known as "development capital") remained primarily the domain of wealthy individuals and families. Only after 1945 did "true" private equity investments begin to emerge, notably with the founding of the first two venture capital firms in 1946: American Research and Development Corporation (ARDC) and J.H. Whitney & Company.[5][6]

text: Georges Doriot, the "father of venture capitalism"[7] (and former assistant dean of Harvard Business School), founded the graduate business school INSEAD in 1957. Along with Ralph Flanders and Karl Compton (former president of MIT), Doriot founded ARDC in 1946 to encourage private-sector investment in businesses run by soldiers returning from World War II. ARDC became the first institutional private-equity investment firm to raise capital from sources other than wealthy families, although it had several notable investment successes as well.[8] ARDC is credited[by whom?] with the first trick when its 1957 investment of $70,000 in Digital Equipment Corporation (DEC) would be valued at over $355 million after the company's initial public offering in 1968 (representing a return of over 1200 times on its investment and an annualized rate of return of 101%).[9]

text: Former employees of ARDC went on to establish several prominent venture-capital firms including Greylock Partners (founded in 1965 by Charlie Waite and Bill Elfers) and Morgan, Holland Ventures, the predecessor of Flagship Ventures (founded in 1982 by James Morgan).[10] ARDC continued investing until 1971, when Doriot retired. In 1972 Doriot merged ARDC with Textron after having invested in over 150 companies.

text: John Hay Whitney (1904–1982) and his partner Benno Schmidt (1913–1999) founded J.H. Whitney & Company in 1946. Whitney had been investing since the 1930s, founding Pioneer Pictures in 1933 and acquiring a 15% interest in Technicolor Corporation with his cousin Cornelius Vanderbilt Whitney. Florida Foods Corporation proved Whitney's most famous investment. The company developed an innovative method for delivering nutrition to American soldiers, later known as Minute Maid orange juice and was sold to The Coca-Cola Company in 1960. J.H. Whitney & Company continued to make investments in leveraged buyout transactions and raised $750 million for its sixth institutional private equity fund in 2005.

text: Early venture capital and the growth of Silicon Valley[edit]

text: One of the first steps toward a professionally managed venture capital industry was the passage of the Small Business Investment Act of 1958. The 1958 Act officially allowed the U.S. Small Business Administration (SBA) to license private "Small Business Investment Companies" (SBICs) to help the financing and management of the small entrepreneurial businesses in the United States.[11]

text: During the 1950s, putting a venture capital deal together may have required the help of two or three other organizations to complete the transaction. It was a business that was growing very rapidly, and as the business grew, the transactions grew exponentially.[12]

text: During the 1960s and 1970s, venture capital firms focused their investment activity primarily on starting and expanding companies. More often than not, these companies were exploiting breakthroughs in electronic, medical, or data-processing technology. As a result, venture capital came to be almost synonymous with technology finance. An early West Coast venture capital company was Draper and Johnson Investment Company, formed in 1962[13] by William Henry Draper III and Franklin P. Johnson, Jr. In 1965, Sutter Hill Ventures acquired the portfolio of Draper and Johnson as a founding action. Bill Draper and Paul Wythes were the founders, and Pitch Johnson formed Asset Management Company at that time.

text: It is commonly noted that the first venture-backed startup is Fairchild Semiconductor (which produced the first commercially practical integrated circuit), funded in 1959 by what would later become Venrock Associates.[14] Venrock was founded in 1969 by Laurance S. Rockefeller, the fourth of John D. Rockefeller's six children, as a way to allow other Rockefeller children to develop exposure to venture capital investments.

text: It was also in the 1960s that the common form of private equity fund, still in use today, emerged. Private equity firms organized limited partnerships to hold investments in which the investment professionals served as general partner and the investors, who were passive limited partners, put up the capital. The compensation structure, still in use today, also emerged with limited partners paying an annual management fee of 1.0–2.5% and a carried interest typically representing up to 20% of the profits of the partnership.

text: The growth of the venture capital industry was fueled by the emergence of the independent investment firms on Sand Hill Road, beginning with Kleiner, Perkins, Caufield & Byers and Sequoia Capital in 1972. Located in Menlo Park, CA, Kleiner Perkins, Sequoia and later venture capital firms would have access to the many semiconductor companies based in the Santa Clara Valley as well as early computer firms using their devices and programming and service companies.[15]

text: Throughout the 1970s, a group of private equity firms, focused primarily on venture capital investments, would be founded that would become the model for later leveraged buyout and venture capital investment firms. In 1973, with the number of new venture capital firms increasing, leading venture capitalists formed the National Venture Capital Association (NVCA). The NVCA was to serve as the industry trade group for the venture capital industry.[16] Venture capital firms suffered a temporary downturn in 1974, when the stock market crashed and investors were naturally wary of this new kind of investment fund.

text: It was not until 1978 that venture capital experienced its first major fundraising year, as the industry raised approximately $750 million. With the passage of the Employee Retirement Income Security Act (ERISA) in 1974, corporate pension funds were prohibited from holding certain risky investments including many investments in privately held companies. In 1978, the US Labor Department relaxed certain restrictions of the ERISA, under the "prudent man rule,"[17] thus allowing corporate pension funds to invest in the asset class and providing a major source of capital available to venture capitalists.

text: The public successes of the venture capital industry in the 1970s and early 1980s (e.g., Digital Equipment Corporation, Apple Inc., Genentech) gave rise to a major proliferation of venture capital investment firms. From just a few dozen firms at the start of the decade, there were over 650 firms by the end of the 1980s, each searching for the next major "home run." The number of firms multiplied, and the capital managed by these firms increased from $3 billion to $31 billion over the course of the decade.[18]

text: The growth of the industry was hampered by sharply declining returns, and certain venture firms began posting losses for the first time. In addition to the increased competition among firms, several other factors affected returns. The market for initial public offerings cooled in the mid-1980s before collapsing after the stock market crash in 1987, and foreign corporations, particularly from Japan and Korea, flooded early-stage companies with capital.[18]

text: In response to the changing conditions, corporations that had sponsored in-house venture investment arms, including General Electric and Paine Webber either sold off or closed these venture capital units. Additionally, venture capital units within Chemical Bank and Continental Illinois National Bank, among others, began shifting their focus from funding early stage companies toward investments in more mature companies. Even industry founders J.H. Whitney & Company and Warburg Pincus began to transition toward leveraged buyouts and growth capital investments.[18][19][20]

text: Venture capital boom and the Internet Bubble[edit]

text: By the end of the 1980s, venture capital returns were relatively low, particularly in comparison with their emerging leveraged buyout cousins, due in part to the competition for hot startups, excess supply of IPOs and the inexperience of many venture capital fund managers. Growth in the venture capital industry remained limited throughout the 1980s and the first half of the 1990s, increasing from $3 billion in 1983 to just over $4 billion more than a decade later in 1994.

text: After a shakeout of venture capital managers, the more successful firms retrenched, focusing increasingly on improving operations at their portfolio companies rather than continuously making new investments. Results would begin to turn very attractive, successful and would ultimately generate the venture capital boom of the 1990s. Yale School of Management Professor Andrew Metrick refers to these first 15 years of the modern venture capital industry beginning in 1980 as the "pre-boom period" in anticipation of the boom that would begin in 1995 and last through the bursting of the Internet bubble in 2000.[21]

text: The late 1990s were a boom time for venture capital, as firms on Sand Hill Road in Menlo Park and Silicon Valley benefited from a huge surge of interest in the nascent Internet and other computer technologies. Initial public offerings of stock for technology and other growth companies were in abundance, and venture firms were reaping large returns.

text: Private equity crash[edit]

text: The Nasdaq crash and technology slump that started in March 2000 shook virtually the entire venture capital industry as valuations for startup technology companies collapsed. Over the next two years, many venture firms had been forced to write-off large proportions of their investments, and many funds were significantly "under water" (the values of the fund's investments were below the amount of capital invested). Venture capital investors sought to reduce the size of commitments they had made to venture capital funds, and, in numerous instances, investors sought to unload existing commitments for cents on the dollar in the secondary market. By mid-2003, the venture capital industry had shriveled to about half its 2001 capacity. Nevertheless, PricewaterhouseCoopers' MoneyTree Survey[22] shows that total venture capital investments held steady at 2003 levels through the second quarter of 2005.

text: Although the post-boom years represent just a small fraction of the peak levels of venture investment reached in 2000, they still represent an increase over the levels of investment from 1980 through 1995. As a percentage of GDP, venture investment was 0.058% in 1994, peaked at 1.087% (nearly 19 times the 1994 level) in 2000 and ranged from 0.164% to 0.182% in 2003 and 2004. The revival of an Internet-driven environment in 2004 through 2007 helped to revive the venture capital environment. However, as a percentage of the overall private equity market, venture capital has still not reached its mid-1990s level, let alone its peak in 2000.

text: Venture capital funds, which were responsible for much of the fundraising volume in 2000 (the height of the dot-com bubble), raised only $25.1 billion in 2006, a 2% decline from 2005 and a significant decline from its peak.[23]

text: Funding[edit]

text: Obtaining venture capital is substantially different from raising debt or a loan. Lenders have a legal right to interest on a loan and repayment of the capital irrespective of the success or failure of a business. Venture capital is invested in exchange for an equity stake in the business. The return of the venture capitalist as a shareholder depends on the growth and profitability of the business. This return is generally earned when the venture capitalist "exits" by selling its shareholdings when the business is sold to another owner.

text: Venture capitalists are typically very selective in deciding what to invest in, with a Stanford survey of venture capitalists revealing that 100 companies were considered for every company receiving financing. [24] Ventures receiving financing must demonstrate an excellent management team, a large potential market, and most importantly high growth potential, as only such opportunities are likely capable of providing financial returns and a successful exit within the required time frame (typically 3–7 years) that venture capitalists expect.

text: Because investments are illiquid and require the extended time frame to harvest, venture capitalists are expected to carry out detailed due diligence prior to investment. Venture capitalists also are expected to nurture the companies in which they invest, in order to increase the likelihood of reaching an IPO stage when valuations are favourable. Venture capitalists typically assist at four stages in the company's development:[25]

text:
Idea generation;
Start-up;
Ramp up; and
Exit

tag: ul

text: Because there are no public exchanges listing their securities, private companies meet venture capital firms and other private equity investors in several ways, including warm referrals from the investors' trusted sources and other business contacts; investor conferences and symposia; and summits where companies pitch directly to investor groups in face-to-face meetings, including a variant known as "Speed Venturing", which is akin to speed-dating for capital, where the investor decides within 10 minutes whether he wants a follow-up meeting. In addition, some new private online networks are emerging to provide additional opportunities for meeting investors.[26]

text: This need for high returns makes venture funding an expensive capital source for companies, and most suitable for businesses having large up-front capital requirements, which cannot be financed by cheaper alternatives such as debt. That is most commonly the case for intangible assets such as software, and other intellectual property, whose value is unproven. In turn, this explains why venture capital is most prevalent in the fast-growing technology and life sciences or biotechnology fields.

text: If a company does have the qualities venture capitalists seek including a solid business plan, a good management team, investment and passion from the founders, a good potential to exit the investment before the end of their funding cycle, and target minimum returns in excess of 40% per year, it will find it easier to raise venture capital.

text: Financing stages[edit]

text: There are typically six stages of venture round financing offered in Venture Capital, that roughly correspond to these stages of a company's development.[27]

text:
Seed funding: The earliest round of financing needed to prove a new idea, often provided by angel investors. Equity crowdfunding is also emerging as an option for seed funding.
Start-up: Early stage firms that need funding for expenses associated with marketing and product development
Growth (Series A round): Early sales and manufacturing funds. This is typically where VCs come in. Series A can be thought of as the first institutional round. Subsequent investment rounds are called Series B, Series C and so on. This is where most companies will have the most growth.
Second-Round: Working capital for early stage companies that are selling product, but not yet turning a profit. This can also be called Series B round and so on.
Expansion: Also called Mezzanine financing, this is expansion money for a newly profitable company
Exit of venture capitalist: VCs can exit through secondary sale or an IPO or an acquisition. Early stage VCs may exit in later rounds when new investors (VCs or Private Equity investors) buy the shares of existing investors. Sometimes a company very close to an IPO may allow some VCs to exit and instead new investors may come in hoping to profit from the IPO.
Bridge Financing is when a startup seeks funding in between full VC rounds. The objective is to raise smaller amount of money instead of a full round and usually the existing investors participate.

text: Between the first round and the fourth round, venture-backed companies may also seek to take venture debt.[28]

text: Firms and funds[edit]

text: Venture capitalists[edit]

text: A venture capitalist is a person who makes venture investments, and these venture capitalists are expected to bring managerial and technical expertise as well as capital to their investments. A venture capital fund refers to a pooled investment vehicle (in the United States, often an LP or LLC) that primarily invests the financial capital of third-party investors in enterprises that are too risky for the standard capital markets or bank loans. These funds are typically managed by a venture capital firm, which often employs individuals with technology backgrounds (scientists, researchers), business training and/or deep industry experience.

text: A core skill within VC is the ability to identify novel or disruptive technologies that have the potential to generate high commercial returns at an early stage. By definition, VCs also take a role in managing entrepreneurial companies at an early stage, thus adding skills as well as capital, thereby differentiating VC from buy-out private equity, which typically invest in companies with proven revenue, and thereby potentially realizing much higher rates of returns. Inherent in realizing abnormally high rates of returns is the risk of losing all of one's investment in a given startup company. As a consequence, most venture capital investments are done in a pool format, where several investors combine their investments into one large fund that invests in many different startup companies. By investing in the pool format, the investors are spreading out their risk to many different investments instead of taking the chance of putting all of their money in one start up firm.

text: Structure[edit]

text: Venture capital firms are typically structured as partnerships, the general partners of which serve as the managers of the firm and will serve as investment advisors to the venture capital funds raised. Venture capital firms in the United States may also be structured as limited liability companies, in which case the firm's managers are known as managing members. Investors in venture capital funds are known as limited partners. This constituency comprises both high-net-worth individuals and institutions with large amounts of available capital, such as state and private pension funds, university financial endowments, foundations, insurance companies, and pooled investment vehicles, called funds of funds.[29]

text: Types[edit]

text: Venture capitalist firms differ in their motivations[30] and approaches. There are multiple factors, and each firm is different.

text: Some of the factors that influence VC decisions include:

text:
Business situation: Some VCs tend to invest in new, disruptive ideas, or fledgling companies. Others prefer investing in established companies that need support to go public or grow.
Some invest solely in certain industries.
Some prefer operating locally while others will operate nationwide or even globally.
VC expectations can often vary. Some may want a quicker public sale of the company or expect fast growth. The amount of help a VC provides can vary from one firm to the next.

text: Roles[edit]

text: Within the venture capital industry, the general partners and other investment professionals of the venture capital firm are often referred to as "venture capitalists" or "VCs". Typical career backgrounds vary, but, broadly speaking, venture capitalists come from either an operational or a finance background. Venture capitalists with an operational background (operating partner) tend to be former founders or executives of companies similar to those which the partnership finances or will have served as management consultants. Venture capitalists with finance backgrounds tend to have investment banking or other corporate finance experience.

text: Although the titles are not entirely uniform from firm to firm, other positions at venture capital firms include:

text:
Position
Role

General Partners or GPs
They run the Venture Capital firm and make the investment decisions on behalf of the fund. GPs typically put in personal capital up to 1-2% of the VC Fund size to show their commitment to the LPs.

Venture partners
Venture partners are expected to source potential investment opportunities ("bring in deals") and typically are compensated only for those deals with which they are involved.

Principal
This is a mid-level investment professional position, and often considered a "partner-track" position. Principals will have been promoted from a senior associate position or who have commensurate experience in another field, such as investment banking, management consulting, or a market of particular interest to the strategy of the venture capital firm.

Associate
This is typically the most junior apprentice position within a venture capital firm. After a few successful years, an associate may move up to the "senior associate" position and potentially principal and beyond. Associates will often have worked for 1–2 years in another field, such as investment banking or management consulting.

Entrepreneur-in-residence
Entrepreneurs-in-residence (EIRs) are experts in a particular industry sector (e.g., biotechnology or social media) and perform due diligence on potential deals. EIRs are hired by venture capital firms temporarily (six to 18 months) and are expected to develop and pitch startup ideas to their host firm, although neither party is bound to work with each other. Some EIRs move on to executive positions within a portfolio company.

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text: Structure of the funds[edit]

text: Most venture capital funds have a fixed life of 10 years, with the possibility of a few years of extensions to allow for private companies still seeking liquidity. The investing cycle for most funds is generally three to five years, after which the focus is managing and making follow-on investments in an existing portfolio. This model was pioneered by successful funds in Silicon Valley through the 1980s to invest in technological trends broadly but only during their period of ascendance, and to cut exposure to management and marketing risks of any individual firm or its product.

text: In such a fund, the investors have a fixed commitment to the fund that is initially unfunded and subsequently "called down" by the venture capital fund over time as the fund makes its investments. There are substantial penalties for a limited partner (or investor) that fails to participate in a capital call.

text: It can take anywhere from a month or so to several years for venture capitalists to raise money from limited partners for their fund. At the time when all of the money has been raised, the fund is said to be closed, and the 10-year lifetime begins. Some funds have partial closes when one half (or some other amount) of the fund has been raised. The vintage year generally refers to the year in which the fund was closed and may serve as a means to stratify VC funds for comparison. This[31] shows the difference between a venture capital fund management company and the venture capital funds managed by them.

text: From investors' point of view, funds can be: (1) traditional—where all the investors invest with equal terms; or (2) asymmetric—where different investors have different terms. Typically the asymmetry is seen in cases where there's an investor that has other interests such as tax income in case of public investors.[32]

text: Compensation[edit]

text: Venture capitalists are compensated through a combination of management fees and carried interest (often referred to as a "two and 20" arrangement):

text:
Payment
Implementation

Management fees
an annual payment made by the investors in the fund to the fund's manager to pay for the private equity firm's investment operations.[33] In a typical venture capital fund, the general partners receive an annual management fee equal to up to 2% of the committed capital.

Carried interest
a share of the profits of the fund (typically 20%), paid to the private equity fund's management company as a performance incentive. The remaining 80% of the profits are paid to the fund's investors[33] Strong limited partner interest in top-tier venture firms has led to a general trend toward terms more favorable to the venture partnership, and certain groups are able to command carried interest of 25–30% on their funds.

text: Because a fund may run out of capital prior to the end of its life, larger venture capital firms usually have several overlapping funds at the same time; doing so lets the larger firm keep specialists in all stages of the development of firms almost constantly engaged. Smaller firms tend to thrive or fail with their initial industry contacts; by the time the fund cashes out, an entirely new generation of technologies and people is ascending, whom the general partners may not know well, and so it is prudent to reassess and shift industries or personnel rather than attempt to simply invest more in the industry or people the partners already know.

text: Alternatives[edit]

text: Because of the strict requirements venture capitalists have for potential investments, many entrepreneurs seek seed funding from angel investors, who may be more willing to invest in highly speculative opportunities, or may have a prior relationship with the entrepreneur.

text: Furthermore, many venture capital firms will only seriously evaluate an investment in a start-up company otherwise unknown to them if the company can prove at least some of its claims about the technology and/or market potential for its product or services. To achieve this, or even just to avoid the dilutive effects of receiving funding before such claims are proven, many start-ups seek to self-finance sweat equity until they reach a point where they can credibly approach outside capital providers such as venture capitalists or angel investors. This practice is called "bootstrapping".

text: Equity crowdfunding is emerging as an alternative to traditional venture capital. Traditional crowdfunding is an approach to raising the capital required for a new project or enterprise by appealing to large numbers of ordinary people for small donations. While such an approach has long precedents in the sphere of charity, it is receiving renewed attention from entrepreneurs, now that social media and online communities make it possible to reach out to a group of potentially interested supporters at very low cost. Some equity crowdfunding models are also being applied specifically for startup funding, such as those listed at Comparison of crowd funding services. One of the reasons to look for alternatives to venture capital is the problem of the traditional VC model. The traditional VCs are shifting their focus to later-stage investments, and return on investment of many VC funds have been low or negative.[26][34]

text: In Europe and India, Media for equity is a partial alternative to venture capital funding. Media for equity investors are able to supply start-ups with often significant advertising campaigns in return for equity. In Europe, an investment advisory firm offers young ventures the option to exchange equity for services investment; their aim is to guide ventures through the development stage to arrive at a significant funding, mergers and acquisition, or other exit strategy.[35]

text: In industries where assets can be securitized effectively because they reliably generate future revenue streams or have a good potential for resale in case of foreclosure, businesses may more cheaply be able to raise debt to finance their growth. Good examples would include asset-intensive extractive industries such as mining, or manufacturing industries. Offshore funding is provided via specialist venture capital trusts, which seek to use securitization in structuring hybrid multi-market transactions via an SPV (special purpose vehicle): a corporate entity that is designed solely for the purpose of the financing.

text: In addition to traditional venture capital and angel networks, groups have emerged, which allow groups of small investors or entrepreneurs themselves to compete in a privatized business plan competition where the group itself serves as the investor through a democratic process.[36]

text: Law firms are also increasingly acting as an intermediary between clients seeking venture capital and the firms providing it.[37]

text: Other forms include venture resources that seek to provide non-monetary support to launch a new venture.

text: Societal impact[edit]

text: Venture capital is also associated with job creation (accounting for 2% of US GDP),[38] the knowledge economy, and used as a proxy measure of innovation within an economic sector or geography. Every year, there are nearly 2 million businesses created in the USA, and 600–800 get venture capital funding. According to the National Venture Capital Association, 11% of private sector jobs come from venture-backed companies and venture-backed revenue accounts for 21% of US GDP.[39]

text: Babson College's Diana Report found that the number of women partners in VC firms decreased from 10% in 1999 to 6% in 2014. The report also found that 97% of VC-funded businesses had male chief executives, and that businesses with all-male teams were more than four times as likely to receive VC funding compared to teams with at least one woman.[40] More than 75% of VC firms in the US did not have any female venture capitalists at the time they were surveyed.[41] It was found that a greater fraction of VC firms had never had a woman represent them on the board of one of their portfolio companies. In 2017 only 2.2% of all VC funding went to female founders.[42]

text: For comparison, a UC Davis study focusing on large public companies in California found 49.5% with at least one female board seat.[43] When the latter results were published, some San Jose Mercury News readers dismissed the possibility that sexism was a cause. In a follow-up Newsweek article, Nina Burleigh asked "Where were all these offended people when women like Heidi Roizen published accounts of having a venture capitalist stick her hand in his pants under a table while a deal was being discussed?"[44][45]

text: Geographical differences[edit]

text: Venture capital, as an industry, originated in the United States, and American firms have traditionally been the largest participants in venture deals with the bulk of venture capital being deployed in American companies. However, increasingly, non-US venture investment is growing, and the number and size of non-US venture capitalists have been expanding.

text: Venture capital has been used as a tool for economic development in a variety of developing regions. In many of these regions, with less developed financial sectors, venture capital plays a role in facilitating access to finance for small and medium enterprises (SMEs), which in most cases would not qualify for receiving bank loans.

text: In the year of 2008, while VC funding were still majorly dominated by U.S. money ($28.8 billion invested in over 2550 deals in 2008), compared to international fund investments ($13.4 billion invested elsewhere), there has been an average 5% growth in the venture capital deals outside the USA, mainly in China and Europe.[46] Geographical differences can be significant. For instance, in the UK, 4% of British investment goes to venture capital, compared to about 33% in the U.S.[47]

text: United States[edit]

text: Venture capitalists invested some $29.1 billion in 3,752 deals in the U.S. through the fourth quarter of 2011, according to a report by the National Venture Capital Association. The same numbers for all of 2010 were $23.4 billion in 3,496 deals.[48]

text: According to a report by Dow Jones VentureSource, venture capital funding fell to $6.4 billion in the USA in the first quarter of 2013, an 11.8% drop from the first quarter of 2012, and a 20.8% decline from 2011. Venture firms have added $4.2 billion into their funds this year, down from $6.3 billion in the first quarter of 2013, but up from $2.6 billion in the fourth quarter of 2012.[49]

text: Mexico[edit]

text: The Venture Capital industry in Mexico is a fast-growing sector in the country that, with the support of institutions and private funds, is estimated to reach US$100 billion invested by 2018.[50]

text: Israel[edit]

text: In Israel, high-tech entrepreneurship and venture capital have flourished well beyond the country's relative size. As it has very little natural resources and, historically has been forced to build its economy on knowledge-based industries, its VC industry has rapidly developed, and nowadays has about 70 active venture capital funds, of which 14 international VCs with Israeli offices, and additional 220 international funds which actively invest in Israel. In addition, as of 2010, Israel led the world in venture capital invested per capita. Israel attracted $170 per person compared to $75 in the USA.[51] About two thirds of the funds invested were from foreign sources, and the rest domestic. In 2013, Wix.com joined 62 other Israeli firms on the Nasdaq.[52] Read more about Venture capital in Israel.

text: Canada[edit]

text: Canadian technology companies have attracted interest from the global venture capital community partially as a result of generous tax incentive through the Scientific Research and Experimental Development (SR&ED) investment tax credit program.[citation needed] The basic incentive available to any Canadian corporation performing R&D is a refundable tax credit that is equal to 20% of "qualifying" R&D expenditures (labour, material, R&D contracts, and R&D equipment). An enhanced 35% refundable tax credit of available to certain (i.e. small) Canadian-controlled private corporations (CCPCs). Because the CCPC rules require a minimum of 50% Canadian ownership in the company performing R&D, foreign investors who would like to benefit from the larger 35% tax credit must accept minority position in the company, which might not be desirable. The SR&ED program does not restrict the export of any technology or intellectual property that may have been developed with the benefit of SR&ED tax incentives.

text: Canada also has a fairly unusual form of venture capital generation in its Labour Sponsored Venture Capital Corporations (LSVCC). These funds, also known as Retail Venture Capital or Labour Sponsored Investment Funds (LSIF), are generally sponsored by labor unions and offer tax breaks from government to encourage retail investors to purchase the funds. Generally, these Retail Venture Capital funds only invest in companies where the majority of employees are in Canada. However, innovative structures have been developed to permit LSVCCs to direct in Canadian subsidiaries of corporations incorporated in jurisdictions outside of Canada.

text: Switzerland[edit]

text: Many Swiss start-ups are university spin-offs, in particular from its federal institutes of technology in Lausanne and Zurich.[53] According to a study by the London School of Economics analysing 130 ETH Zurich spin-offs over 10 years, about 90% of these start-ups survived the first five critical years, resulting in an average annual IRR of more than 43%.[54] Switzerland's most active early-stage investors are The Zurich Cantonal Bank, investiere.ch, Swiss Founders Fund, as well as a number of angel investor clubs.[55]

text: Europe[edit]

text: Europe has a large and growing number of active venture firms. Capital raised in the region in 2005, including buy-out funds, exceeded €60 billion, of which €12.6 billion was specifically allocated to venture investment. Trade association Invest Europe has a list of active member firms and industry statistics.[56]

text: European venture capital investments in 2015 increased by 5% year-on-year to €3.8 billion, with 2,836 companies backed. The amount invested increased across all stages led by seed investments with an increase of 18%. Most capital was concentrated in life sciences (34%), computer & consumer electronics (20%) and communications (19%) sectors, according to Invest Europe's annual data.[57]

text: In 2012, in France, according to a study [58] by AFIC (the French Association of VC firms), €6.1B have been invested through 1,548 deals (39% in new companies, 61% in new rounds) by firms such as Partech Ventures or Innovacom.

text: A study published in early 2013 showed that contrary to popular belief, European startups backed by venture capital do not perform worse than US counterparts.[59] European venture-backed firms have an equal chance of listing on the stock exchange, and a slightly lower chance of a "trade sale" (acquisition by other company).

text: Leading early-stage venture capital investors in Europe include Mark Tluszcz of Mangrove Capital Partners and Danny Rimer of Index Ventures, both of whom were named on Forbes Magazine's Midas List of the world's top dealmakers in technology venture capital in 2007.[60]

text: Asia[edit]

text: India is fast catching up with the West in the field of venture capital and a number of venture capital funds have a presence in the country (IVCA). In 2006, the total amount of private equity and venture capital in India reached $7.5 billion across 299 deals.[61] In the Indian context, venture capital consists of investing in equity, quasi-equity, or conditional loans in order to promote unlisted, high-risk, or high-tech firms driven by technically or professionally qualified entrepreneurs. It is also used to refer to investors "providing seed", "start-up and first-stage financing",[62] or financing companies that have demonstrated extraordinary business potential. Venture capital refers to capital investment; equity and debt ;both of which carry indubitable risk. The risk anticipated is very high. The venture capital industry follows the concept of "high risk, high return", innovative entrepreneurship, knowledge-based ideas and human capital intensive enterprises have taken the front seat as venture capitalists invest in risky finance to encourage innovation.[63]

text: China is also starting to develop a venture capital industry (CVCA).

text: Vietnam is experiencing its first foreign venture capitals, including IDG Venture Vietnam ($100 million) and DFJ Vinacapital ($35 million)[64]

text: Singapore is widely recognized and featured as one of the hottest places to both start up and invest, mainly due to its healthy ecosystem, its strategic location and connectedness to foreign markets.[65] With 100 deals valued at US$3.5 billion, Singapore saw a record value of PE and VC investments in 2016. The number of PE and VC investments increased substantially over the last 5 years: In 2015, Singapore recorded 81 investments with an aggregate value of US$2.2 billion while in 2014 and 2013, PE and VC deal values came to US$2.4 billion and US$0.9 billion respectively. With 53 percent, tech investments account for the majority of deal volume. Moreover, Singapore is home to two of South-East Asia's largest unicorns. Garena is reportedly the highest-valued unicorn in the region with a US$3.5 billion price tag, while Grab is the highest-funded, having raised a total of US$1.43 billion since its incorporation in 2012.[66] Start-ups and small businesses in Singapore receive support from policy makers and the local government fosters the role VCs play to support entrepreneurship in Singapore and the region. For instance, in 2016, Singapore’s National Research Foundation (NRF) has given out grants up to around $30 million to four large local enterprises for investments in startups in the city-state. This first of its kind partnership NRF has entered into is designed to encourage these enterprises to source for new technologies and innovative business models.[67] Currently, the rules governing VC firms are being reviewed by the Monetary Authority of Singapore (MAS) to make it easier to set up funds and increase funding opportunities for start-ups. This mainly includes simplifying and shortening the authorization process for new venture capital managers and to study whether existing incentives that have attracted traditional asset managers here will be suitable for the VC sector. A public consultation on the proposals was held in January 2017 with changes expected to be introduced by July. [68]

text: Middle East and North Africa[edit]

text: The Middle East and North Africa (MENA) venture capital industry is an early stage of development but growing. The MENA Private Equity Association Guide to Venture Capital for entrepreneurs lists VC firms in the region, and other resources available in the MENA VC ecosystem. Diaspora organization TechWadi aims to give MENA companies access to VC investors based in the US.

text: Sub-Saharan Africa[edit]

text: This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (March 2014) (Learn how and when to remove this template message)

text: The Southern African venture capital industry is developing. The South African Government and Revenue Service is following the international trend of using tax efficient vehicles to propel economic growth and job creation through venture capital. Section 12 J of the Income Tax Act was updated to include venture capital. Companies are allowed to use a tax efficient structure similar to VCTs in the UK. Despite the above structure, the government needs to adjust its regulation around intellectual property, exchange control and other legislation to ensure that Venture capital succeeds. <www.savca.co.za>

text: Currently, there are not many venture capital funds in operation and it is a small community; however the number of venture funds are steadily increasing with new incentives slowly coming in from government. Funds are difficult to come by and due to the limited funding, companies are more likely to receive funding if they can demonstrate initial sales or traction and the potential for significant growth. The majority of the venture capital in Sub-Saharan Africa is centered on South Africa and Kenya.

text: Confidential information[edit]

text: Unlike public companies, information regarding an entrepreneur's business is typically confidential and proprietary. As part of the due diligence process, most venture capitalists will require significant detail with respect to a company's business plan. Entrepreneurs must remain vigilant about sharing information with venture capitalists that are investors in their competitors. Most venture capitalists treat information confidentially, but as a matter of business practice, they do not typically enter into Non Disclosure Agreements because of the potential liability issues those agreements entail. Entrepreneurs are typically well advised to protect truly proprietary intellectual property.

text: Limited partners of venture capital firms typically have access only to limited amounts of information with respect to the individual portfolio companies in which they are invested and are typically bound by confidentiality provisions in the fund's limited partnership agreement.

text: Governmental regulations[edit]

text: There are several strict guidelines regulating those that deal in venture capital. Namely, they are not allowed to advertise or solicit business in any form as per the U.S. Securities and Exchange Commission guidelines.[69]

text: In popular culture[edit]

text: In books[edit]

text:
Mark Coggins' novel Vulture Capital (2002) features a venture capitalist protagonist who investigates the disappearance of the chief scientist in a biotech firm in which he has invested. Coggins also worked in the industry and was co-founder of a dot-com startup.[70]
Drawing on his experience as reporter covering technology for the New York Times, Matt Richtel produced the novel Hooked (2007), in which the actions of the main character's deceased girlfriend, a Silicon Valley venture capitalist, play a key role in the plot.[71]
Great, detailed work on VC method of funding. [72]

text: In comics[edit]

text:
In the Dilbert comic strip, a character named "Vijay, the World's Most Desperate Venture Capitalist" frequently makes appearances, offering bags of cash to anyone with even a hint of potential. In one strip, he offers two small children with good math grades money based on the fact that if they marry and produce an engineer baby he can invest in the infant's first idea. The children respond that they are already looking for mezzanine funding.
Robert von Goeben and Kathryn Siegler produced a comic strip called The VC between the years 1997 and 2000 that parodied the industry, often by showing humorous exchanges between venture capitalists and entrepreneurs.[73] Von Goeben was a partner in Redleaf Venture Management when he began writing the strip.[74]

text: In film[edit]

text:
In Wedding Crashers (2005), Jeremy Grey (Vince Vaughn) and John Beckwith (Owen Wilson) are bachelors who create appearances to play at different weddings of complete strangers, and a large part of the movie follows them posing as venture capitalists from New Hampshire.
The documentary Something Ventured (2011) chronicled the recent history of American technology venture capitalists.

text: In television[edit]

text:
In the TV series Dragons' Den, various startup companies pitch their business plans to a panel of venture capitalists.
In the ABC reality television show Shark Tank, venture capitalists ("Sharks") hear entrepreneurs' pitches and select which ones they will invest in.
The short-lived Bravo reality TV show Start-Ups: Silicon Valley had participation from venture capitalists in Silicon Valley.
The sitcom Silicon Valley parodies startup companies and venture capital culture.


document_title: Mandela: Long Walk to Freedom

question_text: who played nelson mandela in the 2013 movie

text: Mandela: Long Walk to Freedom

text: Plot[edit]

text: Based on South African President Nelson Mandela's autobiography of the same name, which chronicles his early life, coming of age, education and 27 years in prison before becoming President and working to rebuild the country's once segregated society.[6]

text: Cast[edit]

text:
Idris Elba as Nelson Mandela
Atandwa Kani as Nelson Mandela (16-23)
Siza Pini as Nelson Mandela (7-9)
Naomie Harris as Winnie Madikizela
Tony Kgoroge as Walter Sisulu
S'Thandiwe Kgoroge as Albertina Sisulu
Riaad Moosa as Ahmed Kathrada
Zolani Mkiva as Raymond Mhlaba
Simo Mogwaza as Andrew Mlangeni
Tshallo Sputla Chokwe as Oliver Tambo
Fana Mokoena as Govan Mbeki
James Cunningham as George Bizos
Thapelo Mokoena as Elias Motsoaledi
Jamie Bartlett as James Gregory
Deon Lotz as Kobie Coetzee
Terry Pheto as Evelyn Mase
Sello Maake as Albert Lutuli
Gys de Villiers as F. W. de Klerk
Zenzo Ngqobe as Patrick Lekota
Carl Beukes as Niel Barnard
A.J. van der Merwe as Fanie van der Merwe
Nomfusi Gotyana as Miriam Makeba
Andre Jacobs as Bram Fischer
Louis van Niekerk as Quartus de Wet
Adam Neill as Percy Yutar
Lindiwe Matshikiza as Zindzi Mandela (28-32)
Refilwe Charles as Zindzi Mandela (8-12)
Semuhle Shangasi as Zenani Mandela (28-32)
Khumbuzile Maphumulo as Zenani Mandela (8-12)
John Herbert as Arthur Goldreich

text: Production[edit]

text: Producer Anant Singh started working on the project after interviewing Mandela while he was still imprisoned two decades prior.[7] Following the publication of Mandela's autobiography, Singh was granted the rights to the film adaptation, which was completed 16 years later by screenwriter William Nicholson. The film is directed by Justin Chadwick.

text: Music[edit]

text: For the film, U2 wrote the song "Ordinary Love".[8] Subscribers of the band's official website were able to hear a short snippet first.[9]

text: Release[edit]

text: The film held its world premiere at the Toronto International Film Festival on 7 September 2013.[7][10] It was released on 28 November 2013 in South Africa and on 3 January 2014 in the United Kingdom, a week before and a month after Mandela died, respectively.

text: Long Walk to Freedom premiered in London on 5 December 2013 as a Royal Film Performance, The Duke and Duchess of Cambridge were in attendance, along with Mandela's daughters Zindzi and Zenani. The announcement of the death of Nelson Mandela occurred while the film was being screened; The Duke and Duchess were immediately informed of Nelson's passing, while producer Anant Singh (alongside Idris Elba) took the stage during the closing credits to inform patrons of Mandela's passing, and held a moment of silence. Prince William made brief comments to the press while exiting the theatre, stating that "I just wanted to say it's extremely sad and tragic news. We were just reminded what an extraordinary and inspiring man Nelson Mandela was. My thoughts and prayers are with him and his family right now." The film was temporarily pulled from theatres in South Africa the next day out of respect, but returned on 7 December 2013.[11][12][13] On the 8th of December to mark the launch of the film a Gala dinner, private screening and charity auction in aid of the children's charity Onetoonechildrensfund. Sir Trevor McDonald was Master of Ceremonies for the evening, introducing the auction where one of a limited edition of 6 portrait heads of Nelson Mandela, sculpted from life by David Cregeen. The head was donated by the sculptor and sold in aid of the charity's work in South Africa.

text: Critical response[edit]

text: On Rotten Tomatoes, the film has an approval rating of 59% based on 123 reviews, with an average rating of 5.9/10. The site's critical consensus reads, "It might be too respectful to truly soar, but there's no denying Idris Elba's impressive work in Mandela: Long Walk to Freedom -- or the inspirational power of the life it depicts."[14] At Metacritic, which assigns a weighted average rating to reviews, the film has an average score of 60 out of 100, based on 32 critics, indicating "mixed or average reviews".[15]

text: Scott Foundas of Variety said the film "never opts for a light touch when a sledgehammer will do", but also praises Elba for "a towering performance, a Mandela for the ages".[16]

text: Claudia Puig of USA Today agreed that Elba's performance was powerful but felt the film was not as strong, stating, "Earnest and ambitious, the film suffers from trying to squeeze in too many milestones of Nelson Mandela's long life as he worked to end the oppressive regime of apartheid in South Africa. But the talent of the lead actors lends it heft, particularly the commanding performance of Idris Elba as Mandela."[17]

text: Jordan Hoffman from Film.com also gave the film a mixed to negative review: "Mandela: Long Walk to Freedom should have been a layup. A slow burn leading to eventual triumph, moving speeches, Idris Elba raging against injustice, the world made a better place because of one man's sacrifice. But as crazy and offensive as it may sound, you'll get more chills from Elba's idiotic speech about canceling the apocalypse in Pacific Rim than you will in this by-the-numbers bore."[18]

text: However, Peter Travers of Rolling Stone gave the film a generally positive review with 2 and a half out of 4 stars, mostly circling the performances.[19]

text: Screenwriter William Nicholson claimed it didn't do better because of the movie 12 Years a Slave: "12 Years a Slave came out in America and that sucked up all the guilt about black people that was available. They were so exhausted feeling guilty about slavery that I don't think there was much left over to be nice about our film." He also speculated that the death of Mandela resulted in a Mandela "overdose" among people, so that they have had enough of him when the movie finally hit the theatres; "Suddenly the word came through that he died. We were deluged with Mandela stuff and after a week we all thought, please, take it away, we've heard enough about Mandela."[20]

text: Historical accuracy[edit]

text: Vincent Hiribarren, a lecturer in world history at King's College London, notes in his review of the film for History Extra, the website of BBC History Magazine: "[The film] clearly depicted Mandela's understanding of the apartheid years. Or, at least, what he wanted to let us know. As the film is not based on Mandela's life but on Mandela's own words, criticism levelled at Mandela's autobiography can also be directed at the film."[21]

text: Turning to the 1976 Soweto uprising, Hiribarren said that the film "did not spend much time evoking this pivotal event, because Mandela did not say much about Soweto in his book. The Soweto uprising was, however, instrumental in creating a new political climate in South Africa that directly led to the politicisation of many young South Africans."[21]

text: Hiribarren awarded the film three stars for historical accuracy, and five for enjoyment.[21]

text: Awards[edit]

text:
Awards

Award
Category
Name
Result

86th Academy Awards
Best Original Song
U2 for "Ordinary Love"
Nominated

ABFF Hollywood Awards
Artist of the Year
Idris Elba (also for Pacific Rim and Thor: The Dark World)
Nominated

71st Golden Globe Awards[22][23]
Best Actor – Motion Picture Drama
Idris Elba
Nominated

Best Original Score
Alex Heffes
Nominated

Best Original Song – Motion Picture
U2 and Danger Mouse ("Ordinary Love")
Won

19th Critics' Choice Awards[24]
Best Song

Nominated

Motion Picture Sound Editors Golden Reel Awards[25][26]
Best Sound Editing: Music Score in a Feature Film
Lewis Morison
Nominated


question_text: when is the major league baseball home run hitting contest

text:
2017 Major League Baseball Home Run Derby

Date
July 10, 2017

Venue
Marlins Park

City
Miami, Florida

Winner
Aaron Judge

Score
11

← 2016
Major League Baseball Home Run Derby
2018 →

text: The 2017 Major League Baseball Home Run Derby was a home run hitting contest between eight batters from Major League Baseball (MLB). The derby was held on July 10, 2017, at Marlins Park in Miami, Florida, the site of the 2017 MLB All-Star Game. On July 5, the participants that will be eligible to participate in the Home Run Derby were announced.[1] Aaron Judge won the Home Run Derby, becoming the first rookie to outright win the event.[2]

text: Rules[edit]

text: Eight players participated in the derby in a bracket-style, single-elimination timed event. Each player had four minutes to hit as many home runs as possible. Hitters were awarded an additional 30 seconds if they hit two home runs over 440 feet (130 m). Hitters were also allowed one 45 second timeout to stop the clock (two in the finals). Homers hit off a T-Mobile Ball during the final minute resulted in a $10,000 donation to charity by T-Mobile & MLB, to the Boys & Girls Clubs of America.

text: The eight competing players were seeded 1-8 based on their home run totals. The higher seed hit second in any round, and the round ended if the higher seed surpassed the total of the first hitter. In the event of a tie, three sets of tiebreakers are employed: first, a 90-second swing-off (with no timeouts nor bonus time awarded); second, each player got three swings; whoever hit more home runs in the three swings would be declared the winner; thereafter, sudden death swings would occur until the tie was broken.[3]

text: Results[edit]

text:
Quarterfinals

Semifinals

Finals

1
Giancarlo Stanton (MIA)
16

8
Gary Sánchez (NYY)
17

8
Gary Sánchez
10

5
Miguel Sanó
11

4
Mike Moustakas (KC)
10

5
Miguel Sanó (MIN)
11

5
Miguel Sanó
10

2
Aaron Judge
11

3
Cody Bellinger (LAD)
15

6
Charlie Blackmon (COL)
14

3
Cody Bellinger
12

2
Aaron Judge
13

2
Aaron Judge (NYY)
23

7
Justin Bour (MIA)
22