Audio signal processor providing simulated source distance control

Claim 2

An audio signal processing system for processing a plurality of channels conducting signals encoded for directional reproduction comprising: input means for receiving input signals; output mixing means for producing an output signal; early reflection simulation means; a first signal path connecting said input means to said output mixing means; and a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; said early reflection simulation means producing, for each of the input signals S from said input means, including an input signal S encoded for reproduction from a non-channel direction, a multiplicity of delayed replicas of said input signal each having a time delay T relative to an arrival time via said first signal path of said input signal S to said output miming means, and having a gain magnitude g S relative to gain of a component corresponding to a first arrival of said input signal S at said output mixing means, said early reflection simulation means and said second signal path having in combination a gain/delay characteristic varying with a parameter d S corresponding to a simulated sound source distance, said gain/delay characteristic characterized by the following equation: g=[1/(1+cT/d.sub.S)]e.sup.-rT, where c is the speed of sound in air, and r is a predetermined constant of absorption per unit time delay which is one of frequency dependent and frequency independent.

Claim 3

Audio signal processing system according to claim 1, wherein said gain magnitude g S is provided by matrix means.

Claim 4

Audio signal processing system according to claim 1, further including matrix means for forming gain magnitude g S proportional to an energy preserving matrix means, which is orthogonal of the first m" columns of an m×m orthogonal matrix means.

Claim 5

Audio signal processing system according to claim 1, wherein each of the input signals is provided with a different simulated sound source distance while sharing the early reflection simulation means in the second signal path.

Claim 6

Audio signal processing system according to claim 1, in which the deviation of said gain magnitude g S from said formula is not greater than 3 dB except when isolated said delayed replicas of said input signal overlap in time cause a greater deviation than 3 dB.

Claim 7

Audio signal processing system according to claim 1, wherein said output mixing means producing a plurality of output signals for directional reproduction, a number of said output signals linearly combined wherein one or more linear combinations of said number of the output signals for other forms of sound reproduction are such that relative gains g s ' in said linear combination signals of simulated early reflections with relative time delay T are either substantially zero or have magnitudes substantially equal to g S ' thereby providing also a simulated distance d S via other forms of sound reproduction.

Claim 8

Audio signal processing system according to claim 6 in which said output signals are provided for stereophonic reproduction via two or more loudspeakers and where said linear combination signals are provided for monophonic or stereophonic reproduction to a fewer number of loudspeakers than provided for the output signals not linearly combined.

Claim 9

Audio signal processing system according to claim 1, in which said early reflection simulation means is additionally provided with energy-preserving linear signal processing means not introducing psychoacoustically significant time delay or attenuation of transients discernable to the human ear.

Claim 10

The system of claim 1, wherein said input signal S encoded for reproduction from a non-channel direction corresponds to a direction of the input signal other than a speaker feed direction.

Claim 11

Audio signal processing system according to claim 1, further including matrix means for forming gain magnitude g S proportional to an energy preserving matrix means, which is unitary of the first m" columns of an m×m unitary matrix means.

Claim 12

Audio signal processing system including signal processing means responsive to an input signal that is from a control means; means for modifying a sound source signal S from a sound source so as to simulate said sound source at a perceived distance d S ; and visual display means arranged to display an image or icon, the apparent distance of said image or icon also being responsive to said control means and varying depending on said distance d S , whereby the perceived distance of the sound source and the apparent distance of said image or icon correspond; said signal processing means comprising: input means for receiving the input signal; output mixing means for producing an output signal; early reflection simulation means; a first signal path connecting said input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delay of a signal in said signal path; said early reflection simulation means producing, for each input signal S from said input means, a multiplicity of delayed replicas of said input signal each having a time delay T relative to an arrival time via said first signal path of said input signal S at said output mixing means, and having a gain magnitude g S relative to a gain via said first signal path of said input signal S at said output mixing means; and said signal modifying means producing modified gain magnitudes g S ' and time delays T' to produce a simulated distance d S ', said early reflection simulation means and said signal modifying means having in combination a gain/delay characteristic varying with a parameter d S corresponding to the simulated sound source distance, said gain/delay characteristic characterized by the following equation: g.sub.S '/g.sub.S =(e.sup.-r't'+gt)(1+cT/d.sub.S)/(1+cT'/d.sub.S ') where c is the speed of sound in air and r and r' are a predetermined respective original and final constants of absorption per unit time delay and both the original and final constants are one of frequency dependent and frequency independent.

Claim 13

Audio signal processing system including signal processing means responsive to an input signal that is from a control means; means for modifying a sound source signal S from a sound source so as to simulate said sound source at a perceived distance d S ; and visual display means arranged to display an image or icon, the apparent distance of said image or icon also being responsive to said control means and varying depending on said distance d S , whereby the perceived distance of the sound source and the apparent distance of said image or icon correspond; said signal processing means comprising: input means for receiving the input signal; output mixing means for producing an output signal; early reflection simulation means; a first signal path connecting said input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delay of a signal in said signal path; said early reflection simulation means producing, for each input signal S from said input means, a multiplicity of delayed replicas of said input signal each having a time delay T relative to an arrival time via said first signal path of said input signal S at said output mixing means, and having a gain magnitude g S relative to a gain via said first signal path of said input signal S at said output mixing means; and said signal modifying means producing modified gain magnitudes g S ' and time delays T' to produce a simulated distance d S ', said early reflection simulation means and said signal modifying means having in combination a gain/delay characteristic varying with a parameter d S corresponding to the simulated sound source distance, said gain/delay characteristic characterized by the following equation: g.sub.S '/g.sub.S =(e.sup.-r't'+gt)(1+cT/d.sub.S)/(1+cT'/d.sub.S ') where c is the speed of sound in air and r and r' are a predetermined respective original and final constants of absorption per unit time delay and both the original and final constants are one of frequency dependent and frequency independent.

Claim 14

Audio signal processing system according to claim 11, wherein said output mixing means producing a plurality of output signals for directional reproduction, a number of said output signals linearly combined wherein one or more linear combinations of the number of said output signals for other forms of sound reproduction are such that the relative gains g S ' in said linear combination signals of simulated early reflections with relative time delay T are either substantially zero or have magnitudes substantially equal to g S ', thereby providing also the simulated distance d S via said other forms of sound reproduction.

Claim 15

An audio signal processing system for processing input signals and outputting an audio output signal giving a simulated distance effect comprising: input means for receiving the input signals; output mixing means for producing the output signal; early reflection simulation a first signal path connecting said input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delay of signals in said signal path, thereby modifying a simulated distance parameter d S ; said early reflection simulation means producing, for each of a plurality of the input signals S from said input means, including an input signal S encoded for reproduction from a non-channel direction, a multiplicity of delayed replicas of said input signal each having a time delay T relative to the arrival time of a component of the input signal corresponding to a first arrival of said input signal at said output mixing means, having a gain magnitude g S relative to gain of said component corresponding to a first arrival of said input signal at said output mixing means, said early reflection simulation means having a gain/delay characteristic varying with said parameter d S corresponding to a simulated sound source distance, said gain/delay characteristic characterized by the following equation: g.sub.s =[1/(1+cT/d.sub.S)]e.sup.-rT, where c is the speed of sound in air, and r is a predetermined constant of absorption per unit time delay which is one of frequency dependent and frequency independent.

Claim 16

An audio signal processing system for processing input signals and outputting an audio output signal giving a simulated distance effect comprising: input means for receiving the input signals; output mixing means for producing the output signal; early reflection simulation a first signal path connecting said input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delay of signals in said signal path, thereby modifying a simulated distance parameter d S ; said early reflection simulation means producing, for each of a plurality of the input signals S from said input means, including an input signal S encoded for reproduction from a non-channel direction, a multiplicity of delayed replicas of said input signal each having a time delay T relative to the arrival time of a component of the input signal corresponding to a first arrival of said input signal at said output mixing means, having a gain magnitude g S relative to gain of said component corresponding to a first arrival of said input signal at said output mixing means, said early reflection simulation means having a gain/delay characteristic varying with said parameter d S corresponding to a simulated sound source distance, said gain/delay characteristic characterized by the following equation: g.sub.s =[1/(1+cT/d.sub.S)]e.sup.-rT, where c is the speed of sound in air, and r is a predetermined constant of absorption per unit time delay which is one of frequency dependent and frequency independent.

Claim 17

The system of claim 13, wherein said signal modifying means are provided in both said first and second signal paths.

Claim 18

The system of claim 13, wherein said signal modifying means modify both gain and time delay of said signals.

Claim 19

A sound mixing system comprising first input means for receiving a plurality of input signals from a plurality of sources, first control means, panning means responsive to said first control means for modifying an input signal received through said first input means from one of the plurality of sources to a desired stereophonic representation, second control means, and distance simulation means responsive to said second control means to further modify said input signal processed by said panning means by producing a signal with simulated reflections characteristic of a desired simulated distance, wherein said distance simulation means comprises: second input means for receiving the input signal from said panning means; output mixing means for producing an output signal; early reflection simulation means; a first signal path connecting said second input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delay of signals in said signal path, thereby modifying a simulated distance parameter d S ; said early reflection simulation means producing for each of the plurality of input signals S a multiplicity of delayed replicas of said input signal each having a time delay T relative to an arrival time via said first signal path of said input signal S to said output mixing means, and having a gain magnitude g S relative to gain via said first signal path of said input signal S at said output mixing means, said early reflection simulation means and said signal modifying means having in combination a gain/delay characteristic varying with the parameter d S corresponding to a simulated sound source distance, said gain/delay characteristic characterized by the following equation; g.sub.s =[1/(1+cT/d.sub.S)]e.sup.-rT, where c is the speed of sound in air, and r is a predetermined constant of absorption per unit time delay which is one of frequency dependent and frequency independent.

Claim 20

A sound mixing system comprising first input means for receiving a plurality of input signals from a plurality of sources, first control means, panning means responsive to said first control means for modifying an input signal received through said first input means from one of the plurality of sources to a desired stereophonic representation, second control means, and distance simulation means responsive to said second control means to further modify said input signal processed by said panning means by producing a signal with simulated reflections characteristic of a desired simulated distance, wherein said distance simulation means comprises: second input means for receiving the input signal from said panning means; output mixing means for producing an output signal; early reflection simulation means; a first signal path connecting said second input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delay of signals in said signal path, thereby modifying a simulated distance parameter d S ; said early reflection simulation means producing for each of the plurality of input signals S a multiplicity of delayed replicas of said input signal each having a time delay T relative to an arrival time via said first signal path of said input signal S to said output mixing means, and having a gain magnitude g S relative to gain via said first signal path of said input signal S at said output mixing means, said early reflection simulation means and said signal modifying means having in combination a gain/delay characteristic varying with the parameter d S corresponding to a simulated sound source distance, said gain/delay characteristic characterized by the following equation; g.sub.s =[1/(1+cT/d.sub.S)]e.sup.-rT, where c is the speed of sound in air, and r is a predetermined constant of absorption per unit time delay which is one of frequency dependent and frequency independent.

Claim 21

Audio signal processing system for processing input signals and outputting audio signals giving a simulated distance effect, comprising: control means; input means for receiving the input signals; output mixing means for producing an output signal; early reflection simulation means responsive to said control means; a first signal path connecting said input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means responsive to said control means, said signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delays of signals in said signal paths, said early reflection simulation means producing for each of the input signals S a multiplicity of delayed replicas of said input signal each having a time delay T relative to an arrival time via said first signal path of said input signal S to said output mixing means, and having a gain magnitude g S , relative to a gain via said first signal path of said input signal S at said outside mixing means, and said signal modifying means producing modified gain magnitudes g S ' and time delays T' to produce a modified simulated distance d S ', said early reflection simulation means and said signal modifying means having in combination a gain/delay characteristic varying with a parameter d S corresponding to a simulated sound source distance, said gain/delay characteristic characterized by the following equation: g.sub.s '/g.sub.s =(e.sup.-r't'+rt)(1+cT/d.sub.S)/(1+cT'/d.sub.S ') where c is the speed of sound in air and r and r' are a predetermined respective original and final constants of absorption per unit time delay and both the original and final constants are one of frequency dependent and frequency.

Claim 22

Audio signal processing system for processing input signals and outputting audio signals giving a simulated distance effect, comprising: control means; input means for receiving the input signals; output mixing means for producing an output signal; early reflection simulation means responsive to said control means; a first signal path connecting said input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means responsive to said control means, said signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delays of signals in said signal paths, said early reflection simulation means producing for each of the input signals S a multiplicity of delayed replicas of said input signal each having a time delay T relative to an arrival time via said first signal path of said input signal S to said output mixing means, and having a gain magnitude g S , relative to a gain via said first signal path of said input signal S at said outside mixing means, and said signal modifying means producing modified gain magnitudes g S ' and time delays T' to produce a modified simulated distance d S ', said early reflection simulation means and said signal modifying means having in combination a gain/delay characteristic varying with a parameter d S corresponding to a simulated sound source distance, said gain/delay characteristic characterized by the following equation: g.sub.s '/g.sub.s =(e.sup.-r't'+rt)(1+cT/d.sub.S)/(1+cT'/d.sub.S ') where c is the speed of sound in air and r and r' are a predetermined respective original and final constants of absorption per unit time delay and both the original and final constants are one of frequency dependent and frequency.

Claim 23

The system of claim 17, wherein r and r' are frequency dependent.

Claim 24

Audio signal processing system according to claim 18, wherein each of the input signals is provided with a different simulated sound source distance while sharing the early reflection simulation means in the second signal path.

Claim 25

The system of claim 17, wherein said signal modifying means are provided in both said first and second signal paths.

Claim 26

The system of claim 17, wherein said signal modifying means modify both gain and time delay of said signals.

Claim 27

Audio signal processing system according to claim 17, wherein the difference between the time delays of simulated early reflections is independent of adjustment of said signal modifying means.

Claim 28

Audio signals processing system according to claim 17, wherein said early reflection simulation means and said signal modifying means affect all components of a source signal S passing through one of said first signal path and said second signal path so as to alter relative gains and delays between the two said signal paths.

Claim 29

Audio signal processing system according to claim 23, wherein said simulated source distance d S is obtained from an original simulated source distance d by said signal modifying means decreasing the relative delay of signals through said second signal path relative to said first signal path by a delay (d s -d)/c and by said signal modifying means multiplying the relative gains of signals through said second signal path relative to said first signal path by (d s /d)exp where a decrease by said relative delay constitutes an increase in the relative gain.

Claim 30

Audio signal processing system according to claim 17, wherein said signal modifying means modifies the gain magnitudes g S ' associated with a time delay T of a simulated reflection giving a first simulated distance d 1 by a factor with amplitude magnitude (1+cT/d.sub.1)/(1+cT/d.sub.2) for every simulated reflection so as to provide a modified early reflection simulation means giving a predetermined second simulated distance d 2 .

Claim 31

Audio signal processing system according to claim 25, wherein said factor with said amplitude magnitude is provided by a matrix means.

Claim 32

Audio signal processing system according claim 17, wherein a reproduced angular spread of the first signal path output of a sound source signal S is varied in response to the value of the simulated distance parameter d S set by the control means.

Claim 33

Audio signal processing system according to claim 17, wherein a perceived loudness of the audio signals is varied by determining at least one of equalization frequency and gain, of the first signal path output in response to the value of the simulated distance d S set by the control means.

Claim 34

Audio signal processing system according to claim 17, wherein an equalization of the first signal path output is varied in response to the value of the simulated distance d S set by the control means.

Claim 35

Audio signal processing system according to claim 17, wherein an energy gain of a simulated reverberant decay is varied in response to the value of the simulated distance d S set by the control means.

Claim 36

Audio signal processing system according to claim 17, wherein an equalization of a reproduced acoustic velocity of the first signal path output of an input signal S is varied in response to the value of the simulated distance d s set by the control means.

Claim 37

Audio signal processing system according to claim 17, wherein a time delay of the first signal path output of an input signal S is varied in response to the value of the simulated distance d s set by the control means.

Claim 38

Audio signal processing system according to claim 32, wherein said control means produces a simulated Doppler effect in said first signal path output.

Claim 39

Audio signal processing system according to claim 17, wherein the control means includes a plurality of channels and means for panning the input signals within said plurality of channels to control a directional effect.

Claim 40

Audio signal processing system according to claim 17, wherein each of the input signals S is provided with a different simulated sound source distance while sharing the early reflection simulation means in said second signal path.

Claim 41

Audio signal processing system according to claim 17, in which the deviation of said gains g S ' from said formula is not greater than 3 dB except when isolated said delayed replicas of said input signal overlap in time cause a greater deviation than 3 b.

Claim 42

Audio signal processing system according to claim 17, in which said early reflection simulation means is additionally provided with energy-preserving linear signal processing means not introducing psychoacoustically significant time delay or attenuation of transients discernable to the human ear.

Claim 43

Audio signal processing system for processing input signals and outputting,an audio signal giving a simulated distance effect, comprising: input means for receiving the input signals; output miming means for producing an output signal; early reflection simulation means; a first signal path connecting said input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delays of signals in said signal path, said early reflection simulation means producing, for each of a plurality of input signals S from said input means, a multiplicity of delayed replicas of said input signal each having a time delay T relative to an arrival time via said first signal path of said input signal S at said output miming means, and having a gain magnitude g S relative to a gain via said first signal path of said input signal S at said output mixing means, and said signal modifying means producing modified gain magnitudes g S ' and time delays T' to produce a modified simulated distance d S ', said early reflection simulation means and said signal modifying means having in combination a gain/delay characteristic varying with a parameter d S corresponding to a simulated sound source distance, said gain/delay characteristic characterized by the following equation: g.sub.s '/g.sub.s =(e.sup.-r'(t'-t) (1+cT/d.sub.S)/(1+cT'/d.sub.S ') where c is the speed of sound in air and r is a predetermined constant of absorption per unit time delay and r' is a predetermined constant of absorption per unit time delay and is one of frequency dependent and frequency of independent.

Claim 44

Audio signal processing system for processing input signals and outputting,an audio signal giving a simulated distance effect, comprising: input means for receiving the input signals; output miming means for producing an output signal; early reflection simulation means; a first signal path connecting said input means to said output mixing means; a second signal path connecting said input means to an input of said early reflection simulation means and connecting an output of said early reflection simulation means to said output mixing means; and signal modifying means provided in one of said first and second signal paths and arranged to modify one of gain magnitude and time delays of signals in said signal path, said early reflection simulation means producing, for each of a plurality of input signals S from said input means, a multiplicity of delayed replicas of said input signal each having a time delay T relative to an arrival time via said first signal path of said input signal S at said output miming means, and having a gain magnitude g S relative to a gain via said first signal path of said input signal S at said output mixing means, and said signal modifying means producing modified gain magnitudes g S ' and time delays T' to produce a modified simulated distance d S ', said early reflection simulation means and said signal modifying means having in combination a gain/delay characteristic varying with a parameter d S corresponding to a simulated sound source distance, said gain/delay characteristic characterized by the following equation: g.sub.s '/g.sub.s =(e.sup.-r'(t'-t) (1+cT/d.sub.S)/(1+cT'/d.sub.S ') where c is the speed of sound in air and r is a predetermined constant of absorption per unit time delay and r' is a predetermined constant of absorption per unit time delay and is one of frequency dependent and frequency of independent.

Claim 45

The system of claim 38, wherein r is frequency dependent.