Optimal Determination of the Truncation Point of Room Impulse Responses

Abstract

A theoretically obtained optimal Truncation Point (TP) in the Room Impulse Response (RIR) is located at the intersection of the main decay slope and the noise floor. Precise determination of this point is difficult in practice. Namely, the deviation of the RIR decay from the exponential decay can lead to discrepancies in the determined TP from the optimal value. In order to increase the accuracy of TP determination, additional terms are incorporated in a simple algorithm. Besides, iterative algorithm for RIR truncation is proposed. These are compared with the existing one, using simulated and measured RIRs. The results confirm the validity of the proposed algorithms, indicating their advantages. In addition, the influences of the response parameters on RIR truncation are investigated.

References

Lundeby

Vigran

T. E.

Bietz

, and Vorländer

: Uncertainties of measurements in room acoustics. Acustica 81 (1995) 344–355.

Bradley

J. S.

, and Soulodre

G. A.

: Objective measures of listener envelopment. J. Acoust. Soc. Am. 98 (1995) 2590–2597.

Schroeder

M. R.

: New method of measuring reverberation time. J. Acoust. Soc. Am. 37 (1965) 409–412.

Otshudi

Guilhot

J. P.

, and Charles

J. L.

: Overview of techniques for measuring impulse response in room acoustics. Proc. of the Institute of Acoustics 10 (1988) 407–414.

Vanderkooy

: Aspects of MLS measuring systems. J. Audio Eng. Soc. 42 (1994) 219–231.

Ćirić

: Determination of Room Acoustical Quantities by Implementation of MLS Technique. (in Serbian) Master's thesis, Faculty of Electronic Engineering, Niš, Yugoslavia, 2000.

Müller

, and Massarani

: Transfer-function measurement with sweeps. J. Audio Eng. Soc. 49 (2001) 443–471.

Stan

G. B.

Embrechts

J. J.

, and Archambeau

: Comparison of different impulse response measurement techniques. J. Audio Eng. Soc. 50 (2002) 249–262.

Vorländer

, and Bietz

: Comparison of methods for measuring reverberation time. Acustica 80 (1994) 205–215.

10.

Kürer

, and Kurze

: Integrationsverfahren zur nachhallauswertung. Acustica 19 (1967/68) 312–322.

11.

Xiang

: Evaluation of reverberation times using a nonlinear regression approach. J. Acoust. Soc. Am. 98 (1995) 2112–2121.

12.

Chu

W. T.

: Comparison of reverberation measurements using Schroeder's impulse method and decay-curve averaging method. J. Acoust. Soc. Am. 63 (1978) 1444–1451.

13.

Morgan

D. R.

: Aparametric error analysis of the backward integration method for reverberation time estimation. J. Acoust. Soc. Am. 101 (1997) 2686–2693.

14.

Ćirić

: Determination of truncation point of room impulse response, Proc. Forum Acusticum, Seville, 2002, (available on CD).

15.

Ćirić

, and Milošević

: Inaccuracies in sound pressure level determination from room impulse response. J. Acoust. Soc. Am. 111 (2002) 210–216.