Some Preliminary Experiments on Binaural Time Delay and Intelligibility

Comparisons are made of the intelligibility of continuous speech in noise under three listening conditions: Speech arriving simultaneously and in phase at the two ears; speech arriving at one ear later than the other; and speech arriving simultaneously, but in opposite phase in one ear. Time intervals between ears ranged from 200 μsec to 7 msec. Delaying speech to one ear under these conditions does increase intelligibility but is little, if any, better than the simple expedient of wiring the phones so that the wave form at one ear is inverted with respect to the other. With the materials and method used, the maximum increase occurs with a delay between ears somewhere between 0.5 and 1 msec, though there is some indication that delays 1 msec and longer may be slightly better under the most difficult listening conditions tried.