US 5,491,754 AGranted

Method and system for artificial spatialisation of digital audio signals

AssigneeFrance Telecom

InventorsJean-Marc Jot, Antoine Chaigne

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Abstract

A method and a system for artificial spatialization of audio-digital signals x(k) making it possible to effect on elementary signals xi(k), replicas of the audio-digital signal, different delays creating delayed elementary signals (seri) summed after weighting with the signal x(k) in order to create the spatialized audio-digital signal y(k). A plurality of linear combinations of the signals (seri) as combined delayed elementary signals (serci) is summed with the elementary signals xi(k). So as to simulate a late reverberation, the linear combinations are effected by a unit loopback, and an attenuation hi(.omega.), a decaying monotonic function of the reverberation time Tr(.omega.) to be simulated and proportional to the delay, is effected with each delay. A spectral correction before weighted summation satisfying the relation: ##EQU1## is effected, .tau.i designating the value of each delay, increased by the phase delay due to the attenuation.

Claims14

Dependent claims

System for processing of a digital audio signal x(k) for creating a spatially processed digital audio signal y(k) comprising:

means for delaying a plurality of elementary signals xi(k) of said digital audio signal x(k) with different delay and for delivering a plurality of delayed elementary signals;
means for linearly combining said delayed elementary signals and for delivering a plurality of combined delayed elementary signals;
means for adding a combined delayed elementary signal with one of said elementary signals xi(k), prior to delaying the latter;
means for weighted summation of said delayed elementary signals and said digital audio signal x(k) in order to create said spatially processed audio-digital signal y(k), wherein said linearly combining means and said adding means constitutes a unitary feedback loop, for which said plurality of combined delayed elementary signals possess the same energy as said delayed elementary signals, said system further including, means for attenuating each delayed elementary signal, as an attenuation Hi(.omega.) function of the audio frequency (.omega.), said attenuation, expressed in decibels, being proportional to each delay and inversely proportional to reverberation time Tr(.omega.);
and
means for spectral correction t(z) of said weighted sum of said attenuated delayed elementary signals, prior to their weighted summation with the audio-digital signal x(k), said spectral correction satisfying the relation:
##EQU22## where .tau.i, defined as the absorbent delay, designates the value of each delay, .SIGMA..tau.i designates the sum of all the absorbent delays, said system constituting a reverberant filter.

4 more elements

Method of processing a digital audio signal x(k) in order to create a spatially processed digital audio signal y(k), comprising the steps of:

duplicating said digital audio signal, into elementary signals xi(k);
subjecting said elementary signals to a plurality of different delays in order to create a plurality of delayed elementary signals seri;
linearly combining said delayed elementary signals in order to obtain a plurality of combined delayed elementary signals serci;
adding at least one of said combined delayed elementary signals to at least one elementary signal xi(k) prior to delaying the latter, said linear combining and said adding forming a feedback loop;
subjecting at least one of said delayed elementary signals seri to a weighted summation with said digital audio signal x(k) in order to create said spatially processed digital audio signal y(k);
and
simulating a late reverberation phenomenon, including:
feeding back said linear combining through a unitary feedback loop, for which said plurality of said combined delayed elementary signals serci possess the same energy as said delayed elementary signals seri;
with each different delay, attenuating said delayed elementary signal seri, said attenuating being dependent on the audio frequency (.omega.), this attenuation, expressed in decibels, being inversely proportional to reverberation time Tr(.omega.) and proportional to each delay;
before said weighted summation of said delayed elementary signals with said digital audio signal x(k), correcting said delayed elementary signals with a spectral corrector t(z) satisfying the relation:
##EQU25## .tau.i, defined as the absorbent delay, designates the value of each delay, .SIGMA..tau.i designating the sum of all the absorbent delays.

8 more elements

Dependencies are inferred from the claim text.