### ASA 126th Meeting Denver 1993 October 4-8

## 4pAA4. A nonlinear regression approach to the evaluation of reverberation
times using Schroeder's integrated impulse response method.

**Ning Xiang
**

**
**
*HEAD Acoust., Kaiserstr. 100, D-5120 Herzogenrath 3, Germany
*

*
*
**W. Ahnert
R. Feistel
**

**
**
*ADA Acoust. Design Ahnert, Berlin, Germany
*

*
*
Reverberation decay curves can be obtained by backward integration of room
impulse responses [M. R. Schroeder, J. Acoust. Soc. Am. 37, 409--412 (1965)].
The evaluation of reverberation times is often achieved by a regression line
fitting the reverberation decay curves. However, the successful application of
this method requires either a careful choice of the integration limit or
estimation of the mean-square value of background noise where background noise
is present in the room impulse responses to be evaluated. In the present paper,
an alternative method for evaluating reverberation times from Schroeder's decay
curves using a nonlinear iterative regression approach is proposed. The
regression process is based on a nonlinear curve model using the generalized
least-square error principle rather than a linear model as used in the linear
regression. The present paper will describe the principle of this approach and
discuss the advantages and disadvantages involved. Comparison of results
obtained using this approach and alternative methods will also be presented.