Abstract
This paper reports real-time subjective listening tests to examine the relationship between the adaptive filter tap length of acoustic echo canceller and the acoustic environmental conditions. A real-time acoustic echo canceller simulation system, for the listening tests, includes two digital filter boards which calculate acoustic echo, pseudo echo, and output error signal by subtracting the pseudo echo from the acoustic echo. Subjects judge whether they could recognize the error signal or not by using several acoustic echo cancellers with tap lengths differ from each other. Reverberation times in the room, signal delay time in telephone line, and noise level in the received signals are varied as parameters. As a result: The tap length mainly depends on reverberation time and delay time in the telecommunication system. The noise affects mildly. And, the maximum range of temporal masking by subject’s voice is estimated as between 0.2 and 0.3 seconds.
