Measurement and Adaptive Identification of Nonstationary Acoustic Impulse Responses

M. Mekarzia

doi:10.1155/2019/4948034

Abstract

In this work, we present a method of measurement of nonstationary acoustic impulse responses identified by the fast version of the Recursive Least Squares algorithm (FRLS), using professional acoustic equipment. This measurement bench realized in a deaf room presents several tests of capability of adaptive algorithm to tracking the nonstationarities of true system to be identified. The tests of tracking capability obtained are stronger compared to what is encountered in real life and can be used in several applications.

Highlights

Acoustic phenomena in an acoustic medium are measured from the notion of the acoustic channel (Figure ), which depends on three main elements: (i) e shape and acoustic properties of the walls and objects in the room (ii) e source with its spectral emission diagram and disposition (LS: loudspeaker)
Our measurements were taken in a room meters long, meters wide, and . meters high. e sound system during the measurements consists of a rotating arm on which are mounted the microphone and a speaker that radiates in the direction of the microphone (Figure )
To check for nonstationarities caused by moving a person into the room, we have identified the signal y(n) from the signal x(n) using the fast recursive least squares algorithm (RLS) with exponential oblivion factor λ

Summary

Introduction

Acoustic phenomena in an acoustic medium are measured from the notion of the acoustic channel (Figure ), which depends on three main elements:. Where h(t) is the impulse response (IR) of the acoustic channels [ , ]. E purpose of the measurement is to find the (IR) h(t) which completely characterizes the acoustic channel. In acoustic rooms, these IR have a duration of the order of one second, and the desired dynamics is of the order of dB. E conventional measurement technique that generates an impulse and records the RI does not allow to simultaneously meet all these requirements [ , ]. We describe the measurement method that is better adapted to the requirements of IR measurement We can apply this method to the impulse response measurement of the individual head [ ]

Impulse Response of the Individual Head

Utilized Equipment e equipment used in the test bench is described as follows:

Description of the Different Measurements Taken