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1. WO2002026000 - A METHOD OF SYNTHESISING AN APPROXIMATE IMPULSE RESPONSE FUNCTION

Publication Number WO/2002/026000
Publication Date 28.03.2002
International Application No. PCT/GB2001/004027
International Filing Date 10.09.2001
Chapter 2 Demand Filed 30.03.2002
IPC
G01S 7/527 2006.01
GPHYSICS
01MEASURING; TESTING
SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
7Details of systems according to groups G01S13/, G01S15/, G01S17/127
52of systems according to group G01S15/58
523Details of pulse systems
526Receivers
527Extracting wanted echo signals
H04S 1/00 2006.01
HELECTRICITY
04ELECTRIC COMMUNICATION TECHNIQUE
SSTEREOPHONIC SYSTEMS
1Two-channel systems
H04S 7/00 2006.01
HELECTRICITY
04ELECTRIC COMMUNICATION TECHNIQUE
SSTEREOPHONIC SYSTEMS
7Indicating arrangements; Control arrangements, e.g. balance control
CPC
G01S 7/527
GPHYSICS
01MEASURING; TESTING
SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
7Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
52of systems according to group G01S15/00
523Details of pulse systems
526Receivers
527Extracting wanted echo signals
H04S 1/005
HELECTRICITY
04ELECTRIC COMMUNICATION TECHNIQUE
SSTEREOPHONIC SYSTEMS 
1Two-channel systems
002Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution
005For headphones
H04S 2420/01
HELECTRICITY
04ELECTRIC COMMUNICATION TECHNIQUE
SSTEREOPHONIC SYSTEMS 
2420Techniques used stereophonic systems covered by H04S but not provided for in its groups
01Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
H04S 7/305
HELECTRICITY
04ELECTRIC COMMUNICATION TECHNIQUE
SSTEREOPHONIC SYSTEMS 
7Indicating arrangements; Control arrangements, e.g. balance control
30Control circuits for electronic adaptation of the sound field
305Electronic adaptation of stereophonic audio signals to reverberation of the listening space
Applicants
  • CENTRAL RESEARCH LABORATORIES LIMITED [GB]/[GB]
Inventors
  • SIBBALD, Alastair
Agents
  • SHARP, Alan, Cooper
Priority Data
0022892.419.09.2000GB
Publication Language English (EN)
Filing Language English (EN)
Designated States
Title
(EN) A METHOD OF SYNTHESISING AN APPROXIMATE IMPULSE RESPONSE FUNCTION
(FR) PROCEDE DE SYNTHESE DE REPONSE IMPULSIONNELLE APPROXIMATIVE
Abstract
(EN)
A method of synthesising an approximate impulse response function from a measured first impulse response function in a given sound field includes: - sampling an early part of the impulse response for the given sound field; synthesising a part impulse response which approximates to the sampled part of the given impulse response by curve fitting using a plurality of basis functions provided by respective multi-tap FIR filters, said part impulse response including scattering artefacts; synthesising subsequent further part impulse responses using the same filters; appyling an envelope function which decrease the amplitude with increasing time, and constructing an extended approximate impulse response by combining successive part impulse responses with irregular overlap to minimise audible artefacts. The synthesised impulse response fuction has psycho-acoustic properties similar to thse of the original impulse response function, and enables fewer taps to be employed.
(FR)
L'invention concerne un procédé de synthèse de réponse impulsionnelle approximative à partir d'une première réponse impulsionnelle de champ acoustique donné, selon les étapes suivantes: échantillonnage d'une partie précoce de la réponse impulsionnelle pour le champ acoustique donné; synthèse d'une réponse impulsionnelle partielle qui équivaut approximativement à la partie échantillonnée de la réponse impulsionnelle considérée, par le biais d'un ajustement de courbe qui repose sur l'utilisation d'une pluralité de fonctions de base issues de filtres respectifs à réponse impulsionnelle finie à prises multiples, sachant que ladite réponse impulsionnelle partielle comporte des artéfacts dus à la dispersion; synthèse des réponses impulsionnelles partielles ultérieures par le biais des mêmes filtres; application d'une enveloppe qui diminue l'amplitude à mesure que la durée augmente, et établissement d'une réponse impulsionnelle approximative étendue par combinaison de réponses impulsionnelles partielles successives avec chevauchement irrégulier, ce qui permet de réduire au minimum les artéfacts audibles. La réponse impulsionnelle synthétisée offre des propriétés psycho-acoustiques similaires à celles de la réponse impulsionnelle originale, et permet de réduire le nombre des prises à utiliser.
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