Appropriate bandwidth and integration time for measurements of the degree of interaural cross correlation as a measure of apparent source width in concert halls

Abstract

ISO 3382 Annex suggests using the degree of interaural cross correlation (ICC) as a measure of apparent source width (ASW), while mentioning that the choice of bandwidth for test signals and the integration time are uncertain. Needless to say, what is important for a physical measure is that it is well correlated with the subjective effect, in this case ASW. This paper describes psychological experiments to investigate the appropriate bandwidth for test signals and the integration time for measuring ICC to evaluate ASW. The experimental results indicate that (1) measurements of ICC with 1/3-oct bands are preferred for evaluating ASW, whereas the use of wide band and 1/1-oct band signals as described in the ISO standard are not, and (2) measurement of ICC for all reflections including both the early reflections and later reverberant sound is most suitable for evaluating ASW, rather than the early reflections alone.