GB2303527A

GB2303527A - Generating binaural sound from audio signals

Info

Publication number: GB2303527A
Application number: GB9614082A
Authority: GB
Inventors: Michael Kohut; Paul Nigel Wood; Jeffrey E Taylor
Original assignee: Sony Pictures Entertainment Inc
Current assignee: Sony Pictures Entertainment Inc
Priority date: 1995-07-13
Filing date: 1996-07-04
Publication date: 1997-02-19
Anticipated expiration: 2016-07-04
Also published as: GB2303527B; JPH09163500A; HK1011826A1; DE19628261A1; GB9614082D0

Description

2303527 GENERATING BINAURAL SOUND The present invention relates to methods

and apparatus for processing sound and, more specifically, to the generation or production of binaural sound or audio. 5 The quality and realism of the sound produced by the sound systems in movie theaters continues to improve. The realism is produced by recording multiple sound tracks and playing back the sound from each of the tracks in speakers that are located in different directions relative to the audience. Currently, many feature films are recorded using seven sound tracks. The seven sound tracks typically include a left 10 surround sound track and a right surround sound track. The left surround sound track is played back through one or more speakers that are behind and to the left of the audience. The right surround sound track is played back through one or more speakers that are behind and to the right of the audience. The remaining five tracks are played back through speakers that are at various angles in front of the audience. 5 Some films have an eighth track that is played back through a subwoofer.

The sound produced by typical home stereo systems does not approach the sound realism provided in movie theaters. Most home stereo systems reproduce stereo sound in two speakers that are typically located in front and to each side of the listener. More sophisticated home stereos are able to reproduce the surround, channels. The most sophisticated home stereo systems have eight or more speakers and can reproduce all eight sound tracks. However, such home stereo systems are relatively expensive.

The sound used in computer applications has also improved. In the past, 5 computer programs did little more than generate beeps with varying durations and frequencies. Currently, some computer programs are able to generate stereo sound with a sound quality that rivals audio CDs. Some sound adapters.allow users to connect sound cards to home stereo equipment so that the sound generated by computer programs (especially computer games) may be reproduced with minimal 0 distortion. In spite of such improvements, the sound produced by computer applications does not approach the sound realism provided in movie theaters.

First to third aspects of the present invention are set forth in claims 1, 9 and 13 hereof, respectively.

A device according to a further aspect of the invention, for producing binaural audio signals from a plurality of audio signals, has a set of inputs for receiving multiple channels of audio. Each input corresponds to a position relative to a listener. The sound signal applied to each input is processed by two sound processing units. One sound processing unit modifies the signal to produce a signal that reflects the frequency response perceived by the right ear of a listener when sound is produced at the position that corresponds to the input. The other sound processing unit modifies the signal to produce a signal that reflects the frequency response perceived by the left ear of a listener when sound is produced at the position that corresponds to the input. Some of the sound processing units impose a delay on the sound signal to reflect the delay perceived by an ear when sound is produced by a source on the other side of the listener. The signals that have been modified to reflect the frequency responses perceived by the right ear are combined to produce a right binaural audio signal. The signals that have been modified to reflect the frequency responses perceived by the left ear are combined to produce a left binaural audio signal.

According to a further aspect of the invention, a first sound signal of a plurality of sound signals is applied to a first frequency response alteration unit and to a first phase delay circuit to produce a first modified signal. A second modified signal is generated based on a second sound signal of the plurality of sound signals. A first. plurality of modified signals, including the first and second modified signals, are combined to produce a first binaural sound signal.

The first sound signal is applied to a second frequency response alteration unit 5 to produce a third modified signal. A fourth modified signal is generated based on the second sound signal of the plurality of sound signals. A second plurality of modified signals are combined to produce a second binaural sound signal, the second plurality of modified signals including the third modified signal and the fourth modified signal. According to another aspect of the invention, a device for producing binaural 10 audio is provided. The device includes a plurality of inputs, a first sound mix unit, a second sound mix unit, and a first and second set of sound processing units. Each input of the plurality of inputs is coupled to the first sound mix unit by a sound processing unit in the first set of sound processing units. Each input of the plurality of inputs is also coupled to the second sound mix unit by a sound processing unit in 15 the second set of sound processing units.

Each sound processing unit corresponds to a position relative to a listener and to an ear of the listener. Each sound processing unit is configured to produce a modified sound signal from a sound signal received from the input to which the sound processing unit is coupled based on the position and the ear that correspond with the 20 sound processing unit. All sound processing units coupled to the same input correspond to the same position. All sound processing units coupled to the first sound mix unit correspond to the right ear of the listener. All sound processing units coupled to the second sound mix unit correspond to the left ear of the listener.

The first sound mix unit is configured to produce a first binaural audio signal by combining a first plurality of modified sound signals produced by the first set of sound processing units. The second sound mix unit is configured to produce a second binaural audio signal by combining a second plurality of modified sound signals produced by the second set of sound processing units.

Preferred embodiments of the invention described hereinbelow provide:

a method and apparatus for electronically embedding directional cues in two channels of sound; a method and apparatus for providing two channels of sound that emulate sound produced from multiple directions; a method and system for recording and reproducing sound that approaches the realism of theater sound systems but does not require expensive sound reproduction equipment; and a method and device for producing binaural audio signals from a plurality of audio signals.

The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

5 Figure 1 is a block diagram of a discrete-to-binaural conversion unit according to one embodiment of the invention; and Figure 2 is a sound system for producing binaural sound channels from eight input sound channels, or from two sound channels which are a result of a process that combines multiple (more than two) sound channels, according to an embodiment of 10 the invention.

The sound waves detected by human ears have different characteristics based on the position of the source of the sound waves relative to the listener. For example, the sound waves generated by a sound source that is located to the front left of a 5 listener will be detected by the left ear before they will be detected by the right ear. In contrast, the sound waves generated by a sound source which is to the front right of a listener will be detected by the left ear after they are detected by the right ear. These timing differences, as well as volume and frequency response differences, provide cues through which the human brain determines the direction from which a sound is 10 produced relative to the listener. Such cues are referred to hereafter as sound direction cues.

In modern movie theaters, listeners perceive that sounds originate from various positions relative to the themselves because the sounds are in fact being reproduced by speakers located at those various positions. For example, a sound that 15 is intended to be heard from the left is played in a speaker located to the left of the audience. Similarly, a sound that is intended to be heard from the back right is played in a speaker located to the back right of the audience.

Feature films typically have numerous sound tracks. Each sound track is intended to be played from a different position relative to the audience. Thus, 20 speakers to the left of an audience may playback one sound track while speakers directly in front of the audience playback another sound track and speakers to the right of the audience play yet another sound track. In sophisticated theaters, eight sound tracks are played back from eight different positions relative to the audience.

-8 Most home sound systems do not support the simultaneous playback of eight sound tracks. Further, the hardware required to surround a listener with eight distinct sound sources (e.g. speakers) to playback the eight sound tracks would be prohibitively expensive. Described hereinbelow are a method and apparatus 5 for recording sound from multiple sound tracks onto two channels of sound in such a way as to reproduce during playback of the two channels of sound the same sound direction cues that would be produced by a state of the art movie theater sound system. Consequently, the sound will be perceived as if it were originating from speakers that surround the listener.

Discrete to Binaural Conversion Referring to Figure 1, it illustrates a discrete-to-binaural conversion unit 100 according to an embodiment of the present invention. Discrete-to- binaural conversion unit 100 has a plurality of inputs 102, 104, 106, 108, 110, 112, 114 and 116 and two 15 outputs 118 and 120. Each of the inputs 102, 104, 106, 108, 110, 112, 114 and 116 is associated with a different position relative to a listener. In the illustrated example, inputs 102, 104, 106, 108, 110, 112, 114 and 116 correspond to the front left, front left center, front center, front right center, front right, back left, back right and subwoofer positions, respectively.

20 Each of the two outputs 118 and 120 correspond to an ear of a listener. In the illustrated example, output 118 corresponds to the left ear and output 120 corresponds to the right ear.

Volume and Frequency Response Cues - The discrete-to-binaural conversion unit 100 further includes a plurality of frequency response alteration units 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150 and 152. Each frequency response alteration unit has 5 an input and an output. The input of each frequency response alteration unit is coupled to one of inputs 102, 104, 106, 108, 110, 112, 114 and 116. The output of each frequency response alteration unit is coupled to one of outputs 118 and 120. Consequently, each frequency response alteration unit is associated with a position/ear combination. For example, frequency response alteration unit 122 is coupled to input 10 102 and output 118. Input 102 is associated with the front left position and output 118 is associated with the left ear. Therefore, frequency response alteration unit 122 is associated with the front left position/left ear combination.

Each frequency response alteration unit is configured to modify the volume and frequency response of a sound signal applied to the input of the frequency 15 response alteration unit to produce a modified sound signal at the output of the frequency response alteration unit. The modification performed by each frequency response alteration unit depends on the position/ear combination with which the frequency response alteration unit is associated. Specifically, each frequency response alteration unit modifies the sound signal at its input to produce a signal that 20 encodes sound as it would be heard by the corresponding ear if the sound were generated from the corresponding position. Thus, frequency response alteration unit 122 modifies the sound signal at its input to produce a modified sound signal that -10 reflects the volume and frequency response that would be perceived by a listeners left. ear if sound where produced from a source located to the front left of the listener.. Referring to Appendix A, it contains graphs illustrating the frequency response detected by each ear when sound is produced from various positions relative to the 5 listener. In each of these figures, the x-axis represents the frequency the y-axis represents the detected response. The response detected by the left ear is represented by a solid line and the response detected by the right ear is represented by a dashed line. Graphs A-1, A-2, A-3, A-4, A-5, A-6 and A-7 respectively illustrate frequency responses detected by each ear when sound is generated from sound sources located 10 to the front left, front left center, front center, front right center, front right, left surround (i.e. left rear), and right surround (i.e. right rear). Graph A-8 represents the frequency response detected by each ear when sound is played on a subwoofer.

Appendixes B and C include tables (B1 to B4, C1 and C2) that contain response values for various frequencies for each position/ear combination. According 15 to one embodiment, the various frequency response alteration units are configured to modify the sound signals applied to their inputs based on the frequency of the sound represented in the sound signals according to the values illustrated in Appendixes B and C. It should be noted, however, that the frequency ranges and frequency response values illustrated in Appendices B and C are merely exemplary.

20 As mentioned above, each input of discrete-to-binaural conversion unit 100 is associated with a particular position. The sound signal that is received on each input is modified by one frequency response alteration unit to produce a first signal that reflects how the left ear would perceive the sound if produced from that particular position, and modified by another frequency response alteration unit to produce a second signal that reflects how the right ear would perceive the sound if produced from the particular position.

Consider, for example, input 102. When a sound signal is applied to input 5 102, the sound signal is modified by frequency response alteration unit 122 and by frequency response alteration unit 138. Frequency response alteration unit 122 modifies the sound to reflect how the left ear would hear the sound if produced from a source directly to the front left of the listener. Frequency response alteration unit 138 modifies the sound to reflect how the right ear would hear the sound if produced from 10 a source directly to the front left of the listener. Thus, when the modified sound signal produced by frequency response alteration unit 122 is played in the left ear of a listener and the modified sound signal produced by frequency response alteration unit 138 is played in the right ear of a listener, a listener perceives the sound to be coming from a sound source directly to the front left of the listener.

Timing Cues The volume and frequency response of sound are not the only sound characteristics that vary based on the position of sound source relative to a listener. The timing at which sound is perceived by each of the ears also changes. For 20 example, a sound produced by a source to the left of a listener will be perceived by the left ear before it is perceived by the right ear. Thus, the sound in the right ear appears delayed. Sound produced by a source to the left center of a listener will also be perceived by the left ear before it is perceived by the right ear. However, the delay -12 between the perceptions made by the two ears will be smaller than when the sound was produced by a source directly to the left of the listener. The closer a sound source is positioned to the center of a listener, the smaller the timing delay between the perceptions. A sound produced from a source directly in front or directly in back of a 5 listener would be perceived by both ears at exactly the same time.

To heighten the perception that sounds are being produced from multiple positions relative to the listener, discrete-to-binaural conversion unit 100 includes a plurality of phase delay units 158, 160, 162, 164, 166, 168 and 170. These phase delay units impose a delay on the sound signal applied to their inputs. Each of the 10 phase delay units is associated with a position/ear combination. The length of the delay imposed by a given phase delay unit is determined by the position/ear combination with which it is associated.

Specifically, each phase delay unit imposes a delay equal to the delay perceived by the ear associated with the phase delay unit, relative to the other ear, 15 when a sound is produced from the position associated with the phase delay unit. For example, phase delay unit 166 is coupled to input 102 and output 120 and therefore is associated with the front left position and the_ right ear. Consequently, phase delay unit 166 imposes a delay equal to the delay perceived by the right ear relative to the left ear when sound is produced from a position directly to the front left of the listener. 20 Phase delay units 166, 168 and 170 are respectively coupled between the inputs 102, 104 and 112 associated with positions to the left of a listener and the output 120 associated with the right ear. Phase delay units 158, 160 and 162 are coupled between the inputs 108, 110 and 114 associated with positions to the right of -13 listener and the output 118 associated with the left ear. While the sound from a subwoofer is not generated from any particular position relative to the listener, a phase delay unit 164 has been placed between the input 116 associated with the subwoofer and the output 118 associated with the left ear to add to the perceived physical size of 5 the sound source.

Binaural Output All of the modified signals produced by the frequency response alteration units and phase delay units associated with the left ear are combined by a left ear mix unit 10 154 to produce a composite signal (a "left binaural signal") that is applied to output 118. All of the modified signals produced by the frequency response alteration units and phase delay units associated with the right ear are combined by a right ear mix unit 156 to produce a second composite signal (a "right binaural signal") that is applied to output 120.

15 When the sound encoded in the left and right binaural signals is played into the left and right ears of a listener, respectively, the listener detects the same sound direction cues (including timing, volume and frequency response) that would be produced by playing the sound signals on inputs 102, 104, 106, 108, 110, 112, 114 and 116 through a sub-woofer speaker, and through speakers located to the front left, 20 front left center, front center, front right center, front right, back left and back right of the listener, respectively. Thus, the sound realism previously available only from movie theater type sound systems is experienced using a two channel sound system.

-14 To ensure the integrity of the sound direction cues detected by thelistener, each of the two playback speakers is preferably acoustically isolated from the other. This acoustic isolation is accomplish, for example, by the use of headphones.

5 Binaural Sound System Referring to Figure 2, it illustrates a sound system 200 according to an embodiment of the invention. Sound system 200 generally includes discrete- tobinaural conversion unit 100, a two-channel to multi-channel conversion unit 202, and a two channel record unit 204. In the illustrated embodiment, two-channel to multi10 channel conversion unit 202 and discrete-to-binaural conversion unit 100 are combined in a single sound signal conversion device 206.

Sound signal conversion device 206 contains two sets of inputs. The first set consists of two inputs 208 and 210. Signals applied to inputs 208 and 210 are transmitted to two-channel to multi-channel conversion unit 202. In the preferred 15 embodiment, these signals are the result of a process that combines multiple (more than two) sound channels into two sound channels (LT and RT) in such a way that the multiple sound channels can be recovered from the two sound channels for repreduction using multiple speakers. In addition to being able to reproduce the sound through multiple speakers, sound system 200 is configured to produce binaural sound.

Two-channel to multi-channel conversion unit 202 is configured to receive two channels of audio from inputs 208 and 210 and to generate therefrom multiple discrete channels of audio. Two-channel to multi-channel conversion unit 202 may be, for -15 example, a signal processing unit such as a Dolby PrologiCTM compatible decoder.

_ The eight channels of audio produced by two-channel to multi-channel conversion unit 202 are generated over a plurality of outputs 228, 230, 232, 234, 236, 238, 240 and 242.

5 The second set of inputs consists of eight inputs 212, 214, 216, 218, 220, 222, 224 and 226. These eight inputs are for receiving eight discrete audio signals from a source external to sound signal conversion device 206.

An eight pole switch 244 selectively couples the inputs of discrete-tobinaural conversion unit 100 to either inputs 212, 214, 216, 218, 220, 222, 224 and 226 or 10 the outputs of two-channel to mull-channel conversion unit 202. When eight pole switch 244 couples the inputs of discrete-to-binaural conversion unit 100 to the outputs of two-channel to mull-channel conversion unit 202, discrete-to-binaural conversion unit 100 produces binaural signals at outputs 118 and. 120 based on the sound signals initially encoded in the two audio channels applied to inputs 208 and 15 210. When eight pole switch 244 is couples the inputs of discreteto-binaural conversion unit 100 to inputs 212, 214, 216, 218, 220, 222, 224 and 226, discreteto-binaural conversion unit 100 produces a binaural audio image of the eight sound channels received at the inputs 212, 214, 216, 218, 220, 222, 224 and 226. Sound signal conversion device 206 includes a second set of outputs in 20 addition to binaural outputs 118 and 120. The second set of outputs includes outputs 246, 248, 250, 252, 254, 256, 258 and 260. These outputs pass through the eight. channels of audio that are applied to the inputs of discrete-to-binaural conversion unit 16 100. Consequently, a listener may select between listening to binaural audio through headphones and playing audio on an system that supports eight-channels of sound. The binaural sound signals generated at outputs 118 and 120 may be recorded by two channel record unit 204 for playback at a later time. A user may connect 5 headphones 262 to two channel record unit 204 to listen to the binaural audio as it is recorded, or may connect headphones 262 directly to outputs 118 and 120 to listen to the binaural audio without recording it.

The present invention has been described above by way of example with numerous references to audio signals. Such audio signals may be digital or analog. 10 Circuitry for converting between digital and analog representations of audio may be added to sound signal conversion device 206 as appropriate for particular implementations. Two channel record unit 204 may reside external to sound signal conversion device 206, as shown, or may be a component within sound signal conversion device 206. The frequency response alteration units and phase delay units 15 may be implemented in a variety of ways. For example, a processor may be programmed to perform the frequency response and phase delay operations described above. Alternately, analog circuitry or hardwired digital circuit may be employed. The present invention is not limited to any specific mode of implementation.

The present invention has also been described above by way of example with 20 reference to eight specific sound source positions (e.g. front left, front center, etc.). These sound source positions are merely exemplary. The number and position of source sources simulated by embodiments of the present invention may vary from application to application. For example, for video games, it may be desirable to process signals on one or more sound channels to cause the sounds to sound as though 17 they are being produced from sound sources above and/or below the listener. While specific embodiments of the present invention have been described, various modifications and substitutions will become apparent by this disclosure. Such modifications and substitutions are within the scope of the present invention, and are intended to be covered by claims which follow appendices A, B and C below.

APPENDIX B a HRTF by Stereo Left Channel 0.20 Khz 0.25 Khz 0.30 Khz 0.32 Khz 0.40 Khz 0.50 Khz 0.60 Khz 0.63 Khz 0.70 Khz 0.80 Khz 0.90 Khz Left Ear 30 0 1.2 Db 1.8 Db 2.3 Db 2.5 Db 3.2 Db 4.0 Db 4.9 Db 5.0 Db 5.4'Db 5.6 Db 5.6 Db Flight Ear -30 0 -0.2 Db 0.2 Db 0.3 Db 0.3 Db 0.0 Db -0.2 Db -0.1 Db -0.1 Db 0.0 Db -0.1 Db -0.6 Db 1.00 Khz 1.20 Khz 1.25 Khz 1.40 Khz 1.60 Khz 1.80. Khz 2.00 Khz 2.30 Khz 2.50 Khz 2.70 Khz 2.90 Khz Left Ear 300 5.3 Db 5.6 Db 5.8 Db 6.8 Db 8.6 Db 11.3 Db 14.3 Db " 19.6 Db 19.9 Db 19.3 Db 18.3 Db Right Ear -30 0 -1.3 Db -1.3 Db -0.9 Db 0.5 Db 3.0 Db 6.2 Db 9.3 Db 12.5 Db 12. 9 Db 12.6 Db 11.4 Db 3.00 Khz 3.20 Khz 3.50 Khz 4.00 Khz 4.50 Khz 5.00 Khz 5.50 Khz 6.00 Khz 6.30 Khz 6.50 Khz Left Ear 30 0 19.1 Db 18.8 Db 18. 4 Db 17.8 Db 16.6 Db 15.2 Db 13.9 Db 12.4 Db 11.5 Db 10.8 Db RI ht Ear - 30 0 10.9 Db 10.1 Db 9.5 Db 8.5 Db 7.1 Db 5.1 Db 3.3 Db 1.8 Db 0.9 Db 0.3 Db -1.1 Db 7.00 Khz 7.50 Khz 8.00 Khz 8.50 Khz 9.00 Khz 9.50 Khz 10.00 Khz 10.50 Khz 11.00 Khz 11.50 Khz 12.00 Khz Left Ear. 300 9.1 Db 7.5 Db 5. 8 Db 4.3 Db 3.1 Db 2.0 Db 2.0 Db 6.1 Db 10.1 Db 11.2 Db 10.1 Db Right Ear -30 0 -1.1 Db -2.1 Db -3.2 Db -4.9 Db -6.9 Db -8.7 Db -9.0 Db -4.5 Db 0.4 Db 3.3 Db 4.5 Db Left Center Channel 0.20 Khz 0.25 Khz 0.30 Khz 0. 32 Khz 0.40 Khz 0.50 Khz 0.60 Khz 0.63 Khz 0.70 Khz 0.80 Khz 0.90 Khz, Left Ear 15 0 0.9 Db 1.4 Db 1.8 Db 1.9 Db 2.3 Db 2.9 Db 3.7 Db 3.8 Db 42 Db 4.4 Db 4.4 Db N 00 Right Ear -150 0.1 Db 0.6 Db 0.8 Db 0.9 Db 0.7 Db 0.7 Db 1.2 Db 1.1 Db 1. 4 Db 1.5 Db 1.2 Db 1.00 Khz 1.20 Khz 1.25 Khz 1.40 Khz 1.60 Khz 1.80 Khz 2.00 Khz 2.30 Khz 2.50 Khz 2.70 Khz 2.90 Khz Left Ear 15 e 4.0 Db 42 Db 4.5 Db 5.5 Db 7.4 Db 10.2 Db 13.2 Db 17.2 Db 18.3 Db 18.6 Db 17.8 Db Right Ear -15 0 0.7 Db 0.9 Db 1.2 Db 2.5 Db 4.7 Db 7.7 Db 10.4 Db 14.0 Db 14.7 Db 14.5 Db 13.4 Db 3.00 Khz 3.20 Khz 3.50 Khz 4.00 Khz 4.50 Khz 5. 00 Khz 5.50 Khz 6.00 Khz 6.30 Khz 6.50 Khz Left Ear 15 e 17.5 Db 17.1 Db 16.9 Db 16.4 Db 14.9 Db 13.1 Db 11.5 Db 9.9 Db 9.0 Db 8.4 Db _ -15 0 13.0 Db 12.4 Db 12.1 Db 11.7 Db 10.2 Db 8.1 Db 6.3 Db 4.7 Db 3.8 Db 3.2 Db Right Ear 7.00 Khz 7.50 Khz 8.00 Khz 8.50 Khz 9.00 Khz 9.50 Khz 10.00 Khz 10.50 Khz 11.00 Khz 11.50 Khz 12.00 Khz Left Ear 15 e 6.7 Db 5.4 Db 3. 9 Db 2.6 Db 1.5 Db 0.5 Db 0.6 Db 4.9 Db 9.1 Db __.10.4 D_b 9.7 Db Right Ear -15 0 1.7 Db 0.6 Db -0.6 Db -1.9 Db -3.3 Db -4.7 Db -4.8 Db -0.5 Db 4. 0 Db 6.1 Db 6.9 Db l B-1 r HRTF by Stereo Center Channel 0.20 Khz 0.25 Khz 0.30 Khz 0.32 Khz 0.40 Khz 0.50 Khz 0.60 Khz 0.63 Khz 0.70 Khz 0.80 Khz 0.90 Khz Left Ear 0 0 0.5 Db 1.0 Db 1.3 Db 1.4 Db 1.5 Db 1.8 Db 2.3 Db 2.4 Db 2.6 Db 3.1 Db 3.0 Db Right Ear 0 e 0.5 Db 1.0 Db 1.3 Db 1.4 Db 1.5 Db 1.8 Db 2.3 Db 2.4 Db 2.8 Db 3.1 Db 3.0 Db 1.00 Khz 1.20 Khz 1.25 Khz 1.40 Khz 1.60 Khz 1.80 Khz 2.00 Khz 2.30 Khz 250 Khi 2.70 Khz 2.90 Khz Left Ear 0 0 2.6 Db 2.7 Db 3.0 Db 4.1 Db 6.1 Db 9.0 Db 12.0 Db 15.9 Db _ 16.8 Db 15.8 Db 16.8 Db Right Ear 0 0 2.6 Db 2.7 Db 3.0 Db 4.1 Db 6.1 Db 9.0 Db 12.0 Db 15.9 Db 16.8 Db 16.8 Db 15.8 Db 3.00 Khz 3.20 Khz 3.50 Khz 4.00 Khz 4.50 Khz 5.00 Khz 5.50 Khz 6.00 Khz 6. 30 Khz 6.50 Khz Left Ear 0 e 15.4 Db 14.9 Db 14.7 Db 14.3 Db 12.8 Db 10.7 Db 8.9 Db. 7.3 Db 6.4 Db 5.8 Db Right Ear 0 0 15.4 Db 14.9 Db 14.7 Db 14. 3 Db 12.8 Db.10.7 Db 8.9 Db 7.3 Db 6.4 Db 5.8 Db 7.00 Khz 7.50 Khz 8.00 Khz 8.50 Khz 9.00 Khz 9.50 Khz 10.00 Khz 10.50 Khz 11.00 Khz 11.50 Khz 12. 00 Khz Left Ear 0 o 4.3 Db 3.1 Db 1.8 Db 0.5 Db -0.6 Db-1.7 Db -1.7 Db 2.5 Db 6. 8 Db 8.4 Db 8.5 Db Right Ear 0 e 4.3 Db 3.1 Db 1.8 Db 0.5 Db -0.6 Db -1.7 Db -1.7 Db 2.5 Db 6.8 Db 8.4 Db 8.5 Db Right Center Channel 0.20 Khz 0.25 Khz 0.30 Khz 0.32 Khz 0.40 Khz 0.50 Khz 0.60 Khz 0.63 Khz 0.70 Khz 0.80 Khz 0.90 Khz Left Ear -15o 0.1 Db 0.6 Db 0.8 Db 0.9 Db 0.7 Db 0.7 Db 1.2 Db 1.1 Db 1.4 Db 1.5 Db 1.2 Db Right Ear 15o 0.9 Db 1.4 Db 1.8 Db 1.9 Db 2.3 Db 2.9 Db 3.7 Db 3.8'Db 4.2 Db _ 4.4 Db 4.4 Db 1.00 Khz 1.20 Khz 1.25 Khz 1.40 Khz 1.60 Khz 1.80 Khz 2.00 Khz 2. 30 Khz 2.50 Khz 2.70 Khz 2.90 Khz Left Ear -15 e 0.7 Db 0.9 Db 1.2 Db 2.5 Db 4.7 Db 7.7 Db 10.4 Db 14.0 Db 14.7 Db 14.5 Db 13.4 Db Right Ear 150 4.0 Db 42 Db 4.5 Db 5.5 Db 7.4 Db 10.2 Db 13.2 Db 17.2 Db 18.3 Db 18.6 Db 17.8 Db 3.00 Khz 3.20 Khz 3.50 Khz 4.00 Khz 4.50 Khz 5.00 Khz 5.50 Khz 6.00 Khz 6. 30 Khz 6.50 Khz Left Ear -1So, 13.0 Db 12.4 Db 12.1 Db 11.7 Db 10.2 Db 8.1 Db 6.3 Db 4.7 Db 3.8 Db 3.2 Db Right Ear 15 e 17.5 Db 17.1 Db 16.9 Db 16.4 Db 14.9 Db 13.1 Db - 11.5 Db 9.9 Db 9.0 Db 8.4 Db 7.00 Khz 7.50 Khz 8.00 Khz 8.50 Khz 9.00 Khz 9.50 Khz 10.00 Khz 10.50 Khz 11.00 Khz 11. 50 Khz 12.00 Khz Left Ear -15 0 1.7 Db 0.6 Db -0.6 Db -1.9 Db -3.3 Db -4.7 Db -4.8 Db -0.5 Db 4.0 Db - 6.1 Db 6.9 Db Right Ear 15 0 6.7 Db 5.4 Db 3.9 Db 2.6 Db 1.5 Db 0.5 Db 0.6 Db 4.9 Db 9. 1 Db 10.4 Db 9.7 Db N o Br2 HRTF by.Stereo Right Channel 0.20 Khz 0.25 Khz 0.30 Khz 0.32 Khz 0.40 Khz 0.50 Khz 0.60 Khz 0.63 Khz 0.70 Khz 0.80' Khz 0.90 Khz Left Ear -30 e -0.2 Db 0.2 Db 0. 3 Db 0.3 Db 0.0 Db -0.2 Db -0.1 Db -0.1 Db 0.0 Db -0.1 Db -0.6 Db RI ht Ear 30 e 1.2 Db 1.8 Db 2.3 Db 2.5 Db 3.2 Db 4.0 Db 4.9 Db 5.0 Db 5.4 Db 5. 6 Db 5.6 Db 1.00 Khz 1.20 Khz 1.25 Khz 1.40 Khz 1.60 Khz 1.80 Khz 2.00 Khz 2.30 Khz 2.50 Khz 2.70 Khz 2.90 Khz Left Ear -30o -1.3 Db -1.3 Db -0. 9 Db 0.5 Db 3.0 Db 6.2 Db 9.3 Db 12.5 Db 12.9 Db 12.6 Db 11.4 Db Right Ear 30 0 5.3 Db 5.6 Db 5.8 Db 6.8 Db 8.6 Db 11.3 Db 14.3 Db 18.3 Db 19.6 Db 19.9 Db 19.3 Db 3.00 Khz 3.20 Khz 3.50 Khz 4.00 Khz 4.50 Khz 5.00 Khz 5.50 Khz 6.00 Khz 6.30 Khz 6.50 Khz Left Ear -30 e 10.9 Db 10.1 Db 9. 5 Db 8.5 Db 7.1 Db 5.1 Db 3.3 Db 1.8 Db 0.9 Db 0.3 Db Right Ear 30o 19.1 Db 18.8 Db 18.4 Db 17.8 Db 16.6 Db 15.2 Db 13.9 Db 12.4 Db 11.5 Db 10.8 Db 7.00 Khz 7.50 Khz 8.00 Khz 8.50 Khz 9.00 Khz 9.50 Khz 10.00 Khz 10.50 Khz 11.00 Khz 11.50 Khz 12.00 Khz Left Ear -30 0 -1.1 Db -2.1 Db -3.2 Db - 4.9 Db -6.9 Db -8.7 Db -9.0 Db -4.5 Db 0.4 Db 3.3 Db 4.5 Db Right Ear 300 9.1 Db 7.5 Db 5.8 Db 4.3 Db 3.1 Db 2.0 Db 2.0 Db 6.1 Db 10.1 Db 11.2 Db 10.1 Db Surround Left Chnl. 0.20 Khz 0.25 Khz 0.30 Khz 0.32 Khz 0.40 Khz 0.50 Khz 0.60 Khz 0.63 Khz 0.70 Khz 0.80 Khz 0.90 Khz Left Ear 165 0 0.7 Db 2.0 Db 1.3 Db 1.4 Db 1.8 Db 2.5 Db 3.4 Db 3.6 Db 4.2 Db 5.0 Db 5.6 Db RI ht Ear -165 0 0.0 Db 0.1 Db 0.1 Db 0.1 Db -0.1 Db 0.1 Db 0.7 Db 0.8 Db 1.4 Db 1.9 Db 2.2 Db 1.00 Khz 1.20 Khz 1.25 Khz 1.40 Khz 1.60 Khz 1.80 Khz 2.00 Khz 2.30 Khz 2.50 Khz 2.70 Khz 2.90 Khz Left Ear 165 0 5.9 Db 6.8 Db 7.1 Db 8.0 Db 8.9 Db 10.2 Db 11.8 Db 14.7 Db 15.3 Db 152 Db 14.3 Db Right Ear -165 0 2.3 Db 2.9 Db 3.2 Db 4.3 Db 5.7 Db 7.0 Db 8.6 Db 11.6 Db 12.4 Db 12.5 Db 11.6 Db 3.00 Khz 3.20 Khz 3.50 Khz 4.00 Khz 4.50 Khz 5.00 Khz 5.50 Khz 6.00 Khz 6.30 Khz 6.50 Khz Left Ear 165 0 14.0 Db 13.4 Db 12.3 Db 10.0 Db 7.5 Db 5.8 Db 4.7 Db 4.0 Db 3.7 Db 3.6 Db Right Ear -165 0 11.2 Db 10.5 Db 9.4 Db 7.6 Db 6.2 Db 4.9 Db 2.5 Db 0. 6 Db -0.2 Db -0.6 Db 7.00 Khz 7.50 Khz 8.00 Khz 8.50 Khz 9.00 Khz 9.50 Khz 10.00 Khz 10.50 Khz 11.00 Khz 11.50 Khz 12.00 Khz Left Ear 165 0 3.5 Db 2.1 Db 0.4 Db -1.3 Db -2.4 Db -3.2 Db -2.7 Db 1.8 Db 6.6 Db 8.2 Db 9.0 Db Right Ear -165 0 -1.4 Db -2.5 Db --4.1 Db -5.9 Db -7.4 Db -8.7 Db -8.6 Db -4.2 Db 0.5 Db 2.5 Db 3.3 Db B-3 w 0 Surround Right Chni. 10.20 Khz Left Ear Fllght-Ear Left Ear Right Ear Left Ear I -165 of 11.2 Db Right Ear I 165 o 14.0 Db Left Ear Right Ear Sub-Wolfer Channel 10.20 Khz Left Ear I 0 o I 0.0 Db Right Ear I 0 o l 0.0 Db Left Ear I 0 o 1 -78.0 Db Right Ear I 0 ol -78.0 Db Left Ear 0 o -78.0 Db Right Ear 0 o -78.0 Db Left Ear I 0 o Right Ear I 0 o -165 0 l 0.0 Db of 0.7 Db 1.00 Khz -165 o I 2.3 Db of 5.9 Db 3.00 Khz 7.00 Khz -165 e I -1.4 Db o I 3.5 Db 0.25 Khzl 0.30 Khz10.32 Khz 0.1 DbI 0.1 DbI 0.1 Db 2.0 DbI 1.3 DbI 1.4 Db 1.20 Khzl 1.25 Khzl 1.40 Khz 2.9 DbI 3.2 DbI 4.3 Db 8.8 DbI 7.1 DbI 8.0 Db 3.20 Khzl' 3.50 Khzl 4.00 Khz 10.5 DbI 9.4 DbI 7.6 Db 13.4 DbI 12.3 DbI 10.0 Db 7.50 Khzl 8.00 Khzl 8.50 Khz -2.5 DbI -4.1 DbI -5.9 Db 2.1 DbI 0.4 DbI -1.3 Db 0.25 Khzl 0.30 Khzl 0.32 Khz -78.0 DbI -78.0 DbI -78.0 Db -78.0 DbI -78.0 DbI -78.0 Db 1.20 Khzl 1.25 Khzl 1.40 Khz 1.00 Khz -78.0 Db -78.0 Db 3.20 Khz 3.00 Khz -78.0 DbI -78.0 DbI -78.0 Db -78.0 DbI -78.0 DbI -78.0 Db 7.50 Khz 8.00 Khz 8.50 Khz -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db - 78.0 Db 7.00 Khz -78.0 Db -78.0 Db -78.0 DbI -78.0 Db -78.0 DbI -78.0 Db 3.50 Khzl 4.00 Khz 0.50 Khz 0.40 Khz 0.1 DbI 0.7 DbI 0.8 Db -0.1 Ob 2.5 DbI 3.4 DbI 3.6 Db 1.8 Db 1.80 Khzl 2.00 Khzl 2.30 Khz 1.60 Khz 7.0 Obl 8.8 DbI 11.6 Db 5.7 Db 10.2 DbI 11.8 DbI - 14.7 Db 8.9 Db 4.50 Khzl 5.00 Khz 6.2 Db 4.9 Db 2.5 Db 0.6 Db 7.5 Db 5.8 Db 4.7 Db 4.0 Db 9.00 Khz19.50 Khzl 10.00 Khzl 10.50 Khz -7.4 DbI -8.7 DbI -8.6 DbI -4.2 Db -2.4 DbI -3.2 DbI -2.7 DbI 1.8 Db 0.40 Khz10.50 K.hz -78.0 DbI -78.0 DbI -78.0 DbI -78.0 Db -78.0 DbI -78.0 DbI -78.0 DbI -78.0 Db 1.60 Khzl 1.80 Khzl 2.00 Khz1 2.30 Khz -78.0 DbI -78.0 DbI -78.0 DbI -78.0 Db -78.0 DbI -78.0 DbI -78.0 DbI -78.0 Db 4.50 Khzl 5.00 Khz -78.0 DbI -78.0 DbI -78.0 DbI -78.0 Db -78.0 Db I -78.0 Db I -78.0 Db I -78.0 Db 9.00 Khz 9.50 Khz 10.00 Khz 10.50 Khz -78.0.Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db 0.60 Khz I 0.63 Khz 5.50 Khzl 6.00 Khz 0.60 Khzl 0.63 Khz 5.50 Khzl 6.00 Khz 0.70 Khz 0.80 Khz 1.4' Db 1.9 Db 5.0 Db 4.2 Db 2.70 Khz 2.50 Khz 12.5 Db 12.4 Db 15.2 Db 15.3 Db 6.50 Khz 6.30 Khz -0.6 Db -0.2 Db 3.6 Db 3.7 Db 11.50 Khz 11.00 Khz 2.5 Db 0.5 Db 8.2 Db 6.6 Db 0.80 Khz 0.70 Khz -78.0 Db -78.0 Db -78.0 Db -78.0 Db 2.70 Khz 2.50 Khz -78.0 Db -78.0 Db -78.0 Db -78.0 Db 6.50 Khz 6.30 Khz -78.0 Db -78.0 Db -78.0 Db -78.0 Db 11.50 Khz -78.0 Db -78.0 Db 11.00 Khz.78.0 Db -78.0 Db 0.90 Khz 2.2 Db 5.6 Db 2.90 Khz 11.6 Db 14.3 Db 12.00 Khz 9.0 Db 0.90 Khz -78.0 Db -78.0 Db -78.0 Db -78.0 Db 12.00 Khz -78.0 Db -78.0 Db B-4 APPENDIX C Hf11F by Stereo Left Ear 0.20 Khz 0.25 Khz 0.30 Khz 0.32 Khz 0.40 Khz 0. 50 Khz 0.60 Khz 0.63 Khz 0.70 Khz 0.80 Khz 0.90 Khz Left 30o 1.2 Db 1.8 Db 2.3 Db 2.5 Db 3.2 Db 4.0 Db 4.9 Db 5.0 Db 5.4.Db - '5.6 Db 5.6 Db Left Center 15 0 0.9 Db 1.4 Db 1.8 Db 1.9 Db 2.3 Db 2.9 Db 3.7 Db 3. 8 Db 4.2 Db 4.4 Db 4.4 Db Center 0 o 0.5 Db 1.0 Db 1.3 Db 1.4 Db 1.5 Db 1.8 Db 2.3 Db 2.4 Db 2. 8 Db 3.1 Db 3.0 Db Right Center -15 0 0.1 Db 0.6 Db 0.8 Db 0.9 Db 0.7 Db 0.7 Db 1.2 Db 1. 1 Db 1.4 Db 1.5 Db 1.2 Db RI ht -30 o -0.2 Db 0.2 Db 0.3 Db 0.3 Db 0.0 Db -0.2 Db -0.1 Db -0.1 Db 0. 0 Db -0.1 Db -0.6 Db Left Surround 165 e 0.7 Db 2.0 Db 1.3 Db 1.4 Db 1.8 Db 2.5 Db 3.4 Db 3. 6 Db 42 Db 5.0 Db 5.6 Db RI ht Surround -165 e 0.0 Db 0.1 Db 0.1 Db 0.1 Db -0.1 Db 0.1 Db 0.7 Db 0. 8 Db 1.4 Db 1.9 Db 2.2 Db Sub-Woffer 0 0 0.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78. 0 Db -78.0 Db -78.0 Db -78.0 Db -78. Db Left Ear 1.00 Khz 1.20 Khz 1.25 Khz 1.40 Khz 1.60 Khz 1.80 Khz 2.00 Khz _ 2.50 Khz 2.70 Khz 2.90 Khz 2.30 Khz Left 3D e 5.3 Db 5.6 Db 5.8-Db 6.8 Db 8.6 Db 11.3 Db 14.3 Db 18. 3 Db 19.6 Db 19.9 Db 19.3 Db Left Center 15 o 4.0 Db 4.2 Db 4.5 Db 5.5 Db 7.4 Db 10.2 Db 13.2 Db 17. 2 Db 18.3 Db 18.6 Db 17.8 Db Center 0 0 2.6 Db 2.7 Db 3.0 Db 4.1 Db 6.1 Db 9.0 Db 12.0 Db 15.9 Db 16. 8 Db 16.8 Db 15.8 Db Right Center -15 0 0.7 Db 0.9 Db 1.2 Db 2.5 Db 4.7 Db 7.7 Db 10.4 Db 14. 0 Db 14.7 Db 14.5 Db 13.4 Db Right -30 o -1.3 Db -1.3 Db -0.9 Db 0.5 Db 3.0 Db 6.2 Db 9.3 Db 12. 5 Db _12.9 Db 12.6 Db 11.4 Db Left Surround 165 e 5.9 Db 6.8 Db 7.1 Db 8.0 Db 8.9 Db 10.2 Db 11.8 Db 14. 7 Db __15.3 Db 15.2 Db 14.3 Db Right Surround -165 0 2.3 Db 2.9 Db 3.2 Db 4.3 Db 5.7 Db 7.0 Db 8.6 Db 11. 6 Db 12.4 Db 12.5 Db 11.6 Db Sub-Woffer 0 e -78.0 Ob -7B.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -7B. 0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db Left Ear 3.00 Khz 3.20 Khz 3.50 Khz 4.00 Khz 4.50 Khz 5.00 Khz 5.50 Khz 6. 00 Khz 6.30 Khz 6.50 Khz Left 30o 19.1 Db 18.8 Db 18.4 Db 17.8 Db 16. 6 Db 15.2 Db 13.9 Db 12.4 Db 11.5 Db 10.8 Db Left Center 15 0 17.5 Db 17. 1 Db 16.9 Db 16.4 Db 14.9 Db 13.1 Db 11.5 Db 9.9 Db 9.0 Db 8. 4 Db Center 0 e 15.4 Db 14.9 Db 14.7 Db 14.3 Db 12.8 Db 10.7 Db 8.9 Db 7. 3 Db 6.4 Db 5.8 Db Right Center -15 0 13.0 Db 12.4 Db 12.1 Db 11.7 Db 10. 2 Db 8.1 Db 6.3 Db 4.7 Db 3.8 Db 3.2 Db Right -30 e 10.9 Db 10.1 Db 9. 5 Db 8.5 Db 7.1 Db 5.1 Db 3.3 Db 1.8 Db 0.9 Db 0.3 Db Left Surround 165 0 14.0 Db 13.4 Db.12.3 Db 10.0 Db 7.5 Db 5.8 Db 4.7 _Db 4.0 Db 3.7 Db 3. 6 Db Right Surround -165 e 11.2 Db 10.5 Db 9.4 Db 7.6 Db 6.2 Db 4.9 Db 2. 5 Db 0.6 Db -0.2 Db -0.6 Db Sub-Woffer 0 o -78.0 Db -78.0 Db -78.0 Db -78. 0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db Left Ear 7. 00 Khz 7.50 Khz 8.00 Khz 8.50 Khz 9.00 Khz 9.50 Khz 10.00 Khz 10. 50 Khz 11.00 Khz 11.50 Khz 12.00 Khz Left 30 0 9.1 Db 7.5 Db 5.8 Db 4.3 Db 3.1 Db 2.0 Db 2.0 Db 6.1 Db 10. 1 Db '11.2 Db 10.1 Db Left Center 15 0 6.7 Db 5.4 Db - 3.9 Db 2.6 Db 1.5 Db 0.5 Db 0.6 Db 4. 9 Db 9.1 Db 10.4 Db 9.7 Db Center 0 0 4.3 Db 3.1 Db 1.8 Db 0.5 Db -0.6 Db -1.7 Db -1.7 Db 2.5 Db 6. 8 Db 8.4 Db 8.5 Db Right Center -15 0 1.7 Db 0.6 Db --0.6 Db -1.9 Db -3.3 Db -4.7 Db -4. 8 Db -0.5 Db 4.0 Db 6.1 Db 6.9 Db Right -30 0 -1.1 Db -2.1 Db -3.2 Db -4.9 Db -6.9 Db -8.7 Db -9.0 Db -4. 5 Db 0.4 Db -- 3.3 Db 4.5 Db Left Surround 165 o 3.5 Db 2.1 Db. 0.4 Db -1.3 Db -2.4 Db -3.2 Db -2. 7 Db 1.8 Db 6.6 Db 8.2 Db 9.0 Db Right Surround -165 0 -1.4 Db -2.5 Db -4.1 Db. -5.9 Db -7.4 Db -8.7 Db -8. 6 Db -4.2 Db 0.5 Db 2. Db 3.3 Db Sub-Woffer 0 o -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78. 0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db w w HRTF by Stereo. Right Ear 0.20 Khz 0.25 Khz 0.30 Khz 0.32 Khz 0.40 Khz 0. 50 Khz 0.60 Khz 0.63 Khz 0.70 Khz 9.80 Khz 0.90 Khz Left -309 -0.2 Db 0.2 Db 0.3 Db 0.3 Db 0.0 Db.-0.2 Db -0.1 Db -0.1 Db 0. 0 Db -0.1 Db -0.6 Db Left Center. -15 9 0.1 Db 0.8 Db 0.8 Db 0.9 Db 0.7 Db 0.7 Db 1.2 Db 1. 1 Db 1.4 Db 1.5 Db 1.2 Db Center 0 9 0.5 Db 1.0 Db 1.3 Db 1.4 Db 1.5 Db 1.8 Db 2.3 Db 2.4 Db 2. 8 Db 3.1 Db 3.0 Db RI ht Center 15 9 0.9 Db 1.4 Db 1.8 Db 1.9 Db 2.3 Db 2.9 Db 3.7 Db 3. 8 Db 4.2 Db 4.4 Db 4.4 Db Right 30 9 1.2 Db 1.8 Db 2.3 Db 2.5 Db 3.2 Db 4.0 Db 4.9 Db 5.0 Db 5. 4 Db 5.6 Db 5.6 Db Left Surround -165 9, Db 0.1 Db 0.1 Db 0.1 Db -0.1 Db 0.1 Ob 0.7 Db 0. 8 Db 1.4 Db 1.9 Db 2.2 Db 0.0 RI ht Surround 165 9 0.7 Db 2.0 Ob - 1.3 Db 1.4 Db 1.8 Db 2.5 Db 3. 4 Db 3.6 Db 4.2 Db 5.0 Db 5.6 Db Sub-Woffer 0 9 0.0 Db -78.0 Db j78.0 Db -78.0 Db -78.0 Db -78.0 Db -78. 0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db Right Ear 1.00 Khz 1.20 Khz 1.25 Khz 1.40 Khz 1.60 Khz 1.80 Khz 2.00 Khz 2.30 Khz 2.50 Khz 2.70 Khz 2.90 Khz Left -30 9 -1.3 Db -1.3 Db -0.9 Db 0.5 Db 3.0 Db 6.2 Db 9.3 Db 12.5 Db 12. 9 Db 12.6 Db 11.4 Db Left Center -15 9 0.7 Db 0.9 Db 1.2 Db 2.5 Db 4.7 Db 7.7 Db 10.4 Db 14. 0 Db 14.7 Db 14.5 Db 13.4 Db Center 0 9 2.6 Db. 2.7 Db 3.0 Db 4.1 Db 6.1 Db 9.0 Db 12.0 Db 15.9 Db 16. 8 Db 16.8 Db 15.8 Db Right Center 15 9 4.0 Db 4.2 Db 4.5 Db 5.5 Db 7.4 Db 10.2 Db 13.2 Db 17. 2 Db 18.3 Db 18.6 Db 17.8 Db Right 300 5.3 Db 5.6 Db 5.8 Db 6.8 Db 8.6 Db 11.3 Db 14.3 Db 18.3 Db 19. 6 Db 19.9 Db 19.3 Ob Left Surround -165 9 2.3 Db 2.9 Db. 3.2 Db 4.3 Db 5.7 Db 7.0 Db 8.6 Db 11. 6 Db 12.4 Db 12.5 Ob 11.6 Db Right Surround 165 9 5.9 Db 6.8 Db 7.1 Db 8.0 Db 8.9 Db 10.2 Db 11. 8 Db 14.7 Db 15.3 Db 15.2 Db 14.3 Db Sub-Woffer 0 9 -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78. 0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db Right Ear 3.00 Khz 3.20 Khz 3.50 Khz 4.00 Khz 4.50 Khz 5.00 Khz 5.50 Khz 6.00 Khz 6.30 Khz 6.50 Khz Left -30o 10.9 Db 10.1 Db - 9.5 Db 8. 5 Db 7.1 Db 5.1 Db 3.3 Db 1.8 Db 0.9 Db 0.3 Db Left Center -15o 13. 0 Db 12.4 Ob 12.1 Db 11.7 Db 10.2 Db 8.1 Db 6.3 Db 4.7 Db 3.8 Db 3. 2 Db Center 0 9 15.4 Db 14.9 Db 14.7 Db 14.3 Db 12.8 bb 10.7 Db 8.9 Db 7. 3 Db 6.4 Db 5.8 Db Right Center 15 e 17.5 Db 17.1 Db 16.9 Db 16.4 Db 14. 9 bb 13.1 Db 11.5 Db 9.9 Db 9.0 Db 8.4 Db Right 30 9 19.1 Db 18.8 Db 18. 4 Db 17.8 Db 16.6 Db 15.2 Db 13.9 Db 12.4 Db 11.5 Db 10.8 Db Left Surround -165 e 11.2 Db 10.5 Db - 9.4 Db 7.6 Db.6.2 Db 4.9 Db 2.5 Db 0. 6 Db -0.2 Db -0.6 Db Right Surround 165 9 14.0 Db 13.4 Db 12.3 Db 10. 0 Db 7.5 Db 5.8 Db 4.7 Db 4.0 Db 3.7 Db 3.6 Db Sub-Woffer 0 9 -78.0 Db - 78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db -78.0 Db - 78.0 Db Right Ear 7.00 Khz 7.50 Khz 8.00 Khz 8.50 Khz 9.00 Khz 9.50 Khz 10.00 Khz 10.50 Khz 11.00 Khz 11.50 Khz 12.00 Khz Left -30o -1.1 Db -2.1 Db -3.2 Db -4.9 Db -6.9 Db -8.7 Db -9.0 Db -4. 5 Db 0.4 Db 3.3 Db 4.5 Db Left Center -15 9 1.7 Db 0.6 Db -0.6 Db -1.9 Db -3.3 Db -4.7 Db -4.8 Db - 0.5 Db 4.0 Ob 6.1 Db 6.9 Db Center 0 9 4.3 Db 3.1 Db 1.8 Db 0.5 Db -0.6 Db -1.7 Db -1.7 Db 2.5 Db 6. 8 Db 8.4 Db 8.5 Db Right Center 15 e 8.7 Db 5.4 Db - Db 2.6 Db 1.5 Db 0.5 Db 0.6 Db 4.9 Db 9. 1 Db 10.4 Db 9.7 Db 3.9 Right 30 9 9.1 Db 7.5 Db 5.8 Db 4.3 Db 3.1 Db 2.0 Db 2.0 Db 6.1 Db 10. 1 Db 11.2 Db 10.1 Db Left Surround -165 e -1.4 Db -2.5 Db.-4.1 Db -5.9 Db -7.4 Db -8.7 Db -8. 8 Db -4.2 Db 0.5 Db 2.5.Db 3.3 Ob RI ht Surround 165 9 3.5 Db 2.1 Db 0.4 Db -1.3 Db -2.4 Db -3.2 Db -2. 7 Db 1.8 Db 6.6 Db 8.2 Db 9.0 Db Sub-Woffer 0 el -78.0 Db -78.0 Db -78.0 DbJ -78.0 Db, -78.0 Db -78.0 Db - 78.0 Db -78.0 Db.78.0 Db -78.0 Db -78.0 Db C-2 w A -35 CLAMS 1 I. A method for generating two binaural sound signals from a plurality of sound 2 signals, the method comprising the steps of:

3 applying a first sound signal of said plurality of sound signals to a first 4 frequency response alteration unit and to a first phase delay unit to 5 produce a first modified signal; 6 generating a second modified signal based on a second sound signal of said 7 plurality of sound signals; 8 combining a first plurality of modified signals to produce a first binaural sound 9 signal, said first plurality of modified signals including said first 10 modified signal and said second modified signal; 11 applying said first sound signal to a second frequency response alteration unit 12 to produce a third modified signal; 13 generating a fourth modified signal based on said second sound signal of said 14 plurality of sound signals; and 15 combining a second plurality of modified signals to produce a second binaural 16 sound signal, said second plurality of modified signals including said 17 third modified signal and said fourth modified signal.

Claims

The method of Claim 1 wherein: said step of generating a second modified signal based on a second sound signal of said plurality of sound signals includes the step of applying 4 said second sound signal of said plurality of sound signals to a third 5 frequency response alteration unit to produce said second modified 6 signal; 7 said step of generating a fourth modified signal based on said second sound 8 signal of said plurality of sound signals comprises the step of applying 9 said second sound signal to a fourth frequency response alteration unit 10 and a second phase delay unit to produce said fourth modified signal. 1 3. The method of Claim 1 wherein: 2 said step of generating a second modified signal based on a second sound 3 signal of said plurality of sound signals includes the step of applying 4 said second sound signal of said plurality of sound signals to a third 5 frequency response alteration unit and a second phase delay unit to 6 produce said second modified signal; 7 said step of generating a fourth modified signal based on said second sound 8 signal of said plurality of sound signals comprises the step of applying 9 said second sound signal to fourth frequency response alteration unit to 10 produce said fourth modified signal; and 11 said fast phase delay unit imposes a different time delay on said first sound 12 signal than said second phase delay unit imposes on said second sound 13 signal. 1 4. The method of Claim 1 wherein -37 2 3 4 5 6 7 8 9 10 I1 said first frequency response alteration unit modifies said first sound signal to cause said first sound signal to reflect a first frequency response, said first frequency response being based on the frequency response perceived by one ear of a person that is located at a first angle relative to a sound source; said second frequency response alteration unit modifies said first sound signal to cause said first sound signal to reflect a second frequency response, said second frequency response being based on the frequency response perceived by the other ear of the person that is located at the first angle relative to the sound source. I 5. The method of Claim 4 wherein: 2 said step of generating a second modified signal based on a second sound 3 signal of said plurality of sound signals includes the step of modifying 4 said second sound signal to cause said second sound signal to reflect a 5 third frequency response, said third frequency response being based 6 on the frequency response perceived by one ear of a person that is 7 located at a second angle relative to a sound source; and 8 said step of generating a fourth modified signal based on said second sound 9 signal of said plurality of sound signals comprises the step of 10 modifying said second sound signal to cause said second sound signal 11 to reflect a fourth frequency response, said fourth frequency response 12 being based on the frequency response perceived by the other ear of -38 13 the person that is located at the second angle relative to the-sound 14 source. 1 6. The method of Claim 1 further comprising the steps of 2 modifying each signal of said plurality of sound signals to produce said first 3 plurality of modified signals; and 4 modifying each signal of said plurality of sound signals to produce said 5 second plurality of modified signals.

1 7. The method of Claim 6 wherein:

2 said step of modifying each signal of said plurality of sound signals to produce

3 said first plurality of modified signals comprises the step of modifying 4 each signal to cause each signal to reflect a frequency response that 5 would be perceived by one ear of a person that is located at various 6 angles relative to various sound sources; and 7 said step of modifying each signal of said plurality of sound signals to produce 8 said second plurality of modified signals comprises the step of 9 modifying each signal to cause each signal to reflect a frequency 10 response that would be perceived by the other ear of the person that is 11 located at the various angles relative to the various sound sources.

-39 1 8. The method of Claim 7 wherein a first set of said plurality of sound signals are 2 associated with one side of said person and a second set of said plurality of 3 sound signals are associated with the other side of said person, wherein:

4 said step of modifying each signal of said plurality of sound signals to produce

5 said first plurality of modified signals comprises the step of imposing a

6 delay on each signal in said first set; and

7 said step of modifying each signal of said plurality of sound signals to produce

8 said second plurality of modified signals comprises the step of

9 imposing a delay on each signal in said second set.

1 9. A device for generating two binaural sound signals based on a plurality of 2 sound signals, the device comprising:

3 a plurality of inputs for receiving said plurality of sound signals; 4 a first set of frequency response alteration units coupled to said plurality of 5 inputs; 6 wherein said first set of frequency response alteration units are configured to 7 modify said plurality of sound signals to produce a first set of modified 8 sound signals; 9 wherein said first set of modified sound signals have frequency responses that

10 reflect how an ear of a listener would perceive the sounds represented

11 in said plurality of sound signals if said sounds were produced by

12 sources at various angles relative to said listener; -40

13 a second set of frequency response alteration units coupled to said. plurality of.

14 inputs;

15 wherein said second set of frequency response alteration units are configured

16 to modify said plurality of sound signals to produce a second set of

17 modified sound signals;

18 wherein said second set of modified sound signals have frequency responses

19 that reflect how the other ear of said listener would perceive the sounds

20 represented in said plurality of sound signals if said sound was 21 produced by sources at said various angles relative to said listener; 22 a first combining circuit coupled to said first set of frequency response 23 alteration units, said first combining circuit combining said first set of 24 modified sound signals to produce a first binaural sound signal; and 25 a second combining circuit coupled to said second set of frequency response 26 alteration units, said second combining circuit combining said second 27 set of modified sound signals to produce a second binaural sound 28 signal.

1 10. The device of Claim 9 wherein:

2 each input of said plurality of inputs corresponds to an angle; 3 the sound signal received at a given input is modified by a frequency response 4 alteration unit in said first set of frequency response alteration units 5 based on said angle relative to said ear; and -41 the sound signal received at a given input is modified by an frequency response alteration unit in said second set of frequency response alteration units based on said angle relative to said other ear.

1 11. The device of Claim 9 further comprising:

2 a first set of phase delay units coupled between selected frequency response 3 alteration units in said first set of frequency response alteration units 4 and said first combining circuit; and 5 a second set of phase delay units coupled between selected frequency response 6 alteration units in said second set of frequency response alteration units 7 and said second combining circuit.

1 12. The device of Claim 11 wherein no input of said plurality of inputs is coupled 2 to both a phase delay unit in said first set of phase delay units and a phase 3 delay unit in said second set of phase delay units.

1 13. A device for producing binaural audio, comprising:

2 a plurality of inputs; 3 a first sound mix unit; 4 a second sound mix unit; 5 a first set of sound processing units, wherein each input of said plurality of 6 inputs is coupled to said first sound mix unit by a sound processing 7 unit in said first set of sound processing units; -42 8 a second set of sound processing units, wherein each input of saidplurality of 9 inputs is coupled to said second sound mix unit by a sound processing 10 unit in said second set of sound processing units; 11 wherein each sound processing unit in said first set of sound processing units 12 and said second set of sound processing units corresponds to a 13 position relative to a listener and to an ear of the listener; 14 wherein each sound processing unit is configured to produce a modified sound 15 signal from a sound signal received from the input to which said sound 16 processing unit is coupled based on the position and the ear that 17 correspond with said sound processing unit; 18 wherein all sound processing units coupled to the same input correspond to the 19 same position; 20 wherein all sound processing units coupled to the first sound mix unit 21 correspond to the right ear of said listener; 22 wherein all sound processing units coupled to the second sound mix unit 23 correspond to the left ear of said listener; 24 wherein said first sound mix unit is configured to produce a first binaural 25 audio signal by combining a first plurality of modified sound signals 26 produced by said first set of sound processing units; and 27 wherein said second sound mix unit is configured to produce a second 28 binaural audio signal by combining a second plurality of modified 29 sound signals produced by said second set of sound processing units.

-43 I 14. The device of Claim 13 wherein each sound processing unit includes a 2 frequency response alteration unit that causes said sound signal received from 3 said input to reflect a frequency response similar to the frequency response 4 perceived by the ear that corresponds to said sound processing unit when 5 sound is produced from the position that corresponds to said sound processing 6 unit.

1 15. The device of Claim 14 wherein at least one of said sound processing units 2 includes a phase delay unit that causes said sound signal received from said 3 input to be delayed based on the ear that corresponds to said sound processing 4 unit and the position that corresponds to said sound processing unit.

1 16. The device of Claim 13 further comprising a plurality of outputs coupled to 2 said plurality of inputs, said plurality of outputs carrying sound signals applied 3 to said plurality of inputs to one or more devices external to said device.

1 17. The device of Claim 13 further including a two-channel to multichannel 2 conversion unit configured produce a plurality of sound signals at a plurality 3 of outputs based on two channels of sound, wherein each output of said 4 plurality of outputs is coupled to said plurality of inputs.

1 18. The device of Claim 17 further comprising:

-44 2 a second plurality of inputs for connecting said plurality of inputs lo one or 3 more devices external to said device; and 4 a switch for selectively connecting to said plurality of inputs either said 5 plurality of outputs or said second plurality of inputs.

1 19. The device of Claim 13 further comprising a recording unit for recording said 2 first binaural audio signal and said second binaural audio signal.

1 20. The device of Claim 13 further comprising a two-channel listening device for 2 listening to said first binaural audio signal and said second binaural audio 3 signal.

21. A method of generating binaural sound signals, the method being substantially as herein described with reference to the accompanying drawings.

22. Apparatus for generating binaural sound signals, the apparatus being substantially as herein described with reference to the accompanying drawings.

Tile ellt Office 1'z ? Application No: GB 9614082.7 Examiner: Mr B J Spear Claims searched: 13-20 Date of search: 7 January 1997 Patents Act 1977 Further Search Report under Section 17 Databases searched:

UK Patent Office collections, including GB, EP, WO & US patent specifications, in: UK Cl (Ed.0): H4R (RSAD, RSDX, RSEX, RSS, RSX) Int Cl (Ed.6): H04R 5/04; H04S 1/00 Other: Online: WPI Documents considered to be relevant:

Categoryl Identity of document and relevant passage Relevant to claims X I GB2224186A (AKG) whole document,eg Fig. 4 and p 9 line 15 to p 10 line 18.

13,15,and 20 at least X Document indicating lack of novelty or inventive step A Document indicating technological background and/or state of the an.

Y Document indicating lack of inventive step if combined P Document published on or after the declared priority date but before with one or more other documents of same category. the filing date of this invention.

E Patent document published on or after, but with priority date earlier & Member of the same patent family than, the filing date of this application.

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