EP0357402A2
Expired / Lapsed
EP
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Sound imaging method and apparatus
Assignee: Qsound Ltd
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Filing: 1989-08-30
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Granted: —
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Expires: 2009-08-30
Abstract
Abstract The illusion of distinct sound sources distributed throughout the three-dimensional space containing the listener is possible using only conventional stereo playback equipment by processing monaural sound signals prior to playback on two spaced-apart transducers. A plurality of such processed signals corresponding to different sound source positions may be mixed using conventional techniques without disturbing the positions of the individual images. Although two loudspeakers are required the sound produced is not conventional stereo, however, each channel of a left/right stereo signal can be separately processed according to the invention and then combined for playback. The sound processing involves dividing each monaural or single channel signal into two signals and then adjusting the differential phase and amplitude of the two channel signals on a frequency dependent basis in accordance with an empirically derived transfer function that has a specific phase and amplitude adjustment for each predetermined frequency interval over the audio spectrum. Each transfer function is empirically derived to relate to a different sound source location and by providing a number of different transfer functions and selecting them accordingly the sound source can be made to appear to move.
Inventors
- 👤 Danny D. Lowe
- 👤 John W. Lees
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 23:12
CPC Classifications
H; H04; H04R; H04R5/00; H04R5/02; H04S; H04S5/00; H04S1/00; H04S1/002; H04S2400/00; H04S2400/01; H04S2420/00; H04S2420/03; H04S7/00; H04S7/40
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
159 words
A method for producing and locating an apparent origin of a selected sound from an electrical signal corresponding to the selected sound in a predetermined and localized position anywhere within the three-dimensional space containing a listener, comprising the steps of: separating said electrical signal into respective first and second channel signals; altering the amplitude and shifting the phase of the signal in at least one of said first and second channels, both on a predetermined frequency dependent basis, thereby producing at least a first channel or a second channel modified signal and creating a differential phase and amplitude between the two channel signals; and respectively applying at least first and second channel modified signals to first and second sound transducer means located within the three-dimensional space and spaced apart from the listener to produce a sound apparently originating at a predetermined location in the three dimensional space that may be different from the location of said sound transducer means.
Claim 2
Independent Claim
159 words
A method for producing and locating an apparent origin of a selected sound from an electrical signal corresponding to the selected sound in a predetermined and localized position anywhere within the three-dimensional space containing a listener, comprising the steps of: separating said electrical signal into respective first and second channel signals; altering the amplitude and shifting the phase of the signal in at least one of said first and second channels, both on a predetermined frequency dependent basis, thereby producing at least a first channel or a second channel modified signal and creating a differential phase and amplitude between the two channel signals; and respectively applying at least first and second channel modified signals to first and second sound transducer means located within the three-dimensional space and spaced apart from the listener to produce a sound apparently originating at a predetermined location in the three dimensional space that may be different from the location of said sound transducer means.
Claim 3
Dependent Claim
37 words
The method of claim 1 wherein the step of altering the amplitude and shifting the phase of said signals is applied to both said first and second channel signals while maintaining said phase and amplitude differential therebetween.
Claim 4
Dependent Claim
58 words
The method of claim 1 further including the step of applying at least one of said first and second channel signals to at least one all pass filter containing an operational amplifier portion, said filter having a predetermined frequency response and topology as characterized by an empirically derived transfer function T(s) for the Laplace complex frequency variable (s).
Claim 5
Dependent Claim
38 words
The method of claim 3 wherein the step of applying at least one of said signals to at least one filter includes the further step of applying said at least one signal to a cascaded series of filters.
Claim 6
Dependent Claim
36 words
The method of claim 1 further including the step of storing said first and second channel signals and modified signals derived therefrom in a medium capable of regenerating said stored signals at a subsequent selected time.
Claim 7
Dependent Claim
55 words
The method of claim 1 wherein the step of altering the amplitude and shifting the phase includes passing at least one of said first and second channels through a sound processor having a predetermined phase transfer function to effect said differential phase shift and a predetermined amplitude transfer function to effect said differential amplitude alteration.
Claim 8
Dependent Claim
24 words
The method of claim 6, wherein the predetermined phase and amplitude transfer functions are constructed on a frequency dependent basis of 40 Hz intervals.
Claim 9
Independent Claim
138 words
A system for conditioning a signal for producing and locating, using two transducers located in free space, an auditory sensory illusion of an apparent origin for at least one selected sound at a predetermined and localized position located within the three-dimensional space containing a listener from an electrical signal corresponding to the selected sound, comprising: first and second channel means both receiving the electrical signal, one of said first and signal channel means including means for altering the amplitude and shifting the phase angle of the respective electrical signal on a frequency dependent basis to produce a respective modified signal therefrom such that wherein the amplitude and phase shift differential occurring between the two channels is a predetermined value for each frequency interval of the audio spectrum, said first and second channels being fed to the two transducers.
Claim 10
Independent Claim
138 words
A system for conditioning a signal for producing and locating, using two transducers located in free space, an auditory sensory illusion of an apparent origin for at least one selected sound at a predetermined and localized position located within the three-dimensional space containing a listener from an electrical signal corresponding to the selected sound, comprising: first and second channel means both receiving the electrical signal, one of said first and signal channel means including means for altering the amplitude and shifting the phase angle of the respective electrical signal on a frequency dependent basis to produce a respective modified signal therefrom such that wherein the amplitude and phase shift differential occurring between the two channels is a predetermined value for each frequency interval of the audio spectrum, said first and second channels being fed to the two transducers.
Claim 11
Dependent Claim
50 words
The system as in claim 8 further including second means in the other channel for producing a second modified signal, wherein the alteration of amplitude and phase shift occurring in said second modified signal is also done in a frequency dependent manner and amplitude and phase shift differential is maintained.
Claim 12
Dependent Claim
35 words
A system as in claim 8 further including storage means connected to said means for altering for storing said modified signals in a medium capable of regenerating said stored signals at a subsequent selected time.
Claim 13
Dependent Claim
51 words
A system as in claim 8 wherein the means for latering the amplitude and shifting the phase comprises a sound processor having a predetermined amplitude transfer functions for producing the differential on frequency dependent basis and having a predetermined phase transfer function for producing the differential on a frequency dependent basis.
Claim 14
Dependent Claim
18 words
A system as in claim 11, wherein the frequency dependent basis is made up of 40 Hz intervals.
References Cited (Backward Citations)
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