Squelch of room effects in everyday conversation

Abstract

When a conversation is recorded and then played back, listeners are aware of effects of the room that are not perceived in face-to-face conversation. The room effects, which are physically present, are said to be “squelched” under face-to-face conditions. Room effects include reverberation and coloration caused by reflections. The squelch effect has been attributed to the binaural nature of natural listening, based on binaural experiments with headphones [W. Koenig, J. Acoust. Soc. Am., {22}, 61–62 (1950)]. We report experiments on binaural and diotic listening to recordings of speech made at conversational distances in a room with normal frequency dependence of reverberation and a direct to reverberant power ratio between 1/2 and 1/3 at speech fundamental frequencies. Recordings were made with and without a head between the microphones. Listeners ranked the recordings in order of increasing perceived room effects. The data revealed a strong effect of distance, a weak effect of head diffraction, and an advantage for binaural listening somewhat smaller than the advantage of a factor of 2 in direct power. For a few listeners, binaural listening enhanced the room effects. The latter listeners apparently found that binaural differences produced especially prominent spatial effects. [Work supported by the AFOSR.]