Intelligibility and listener preference of telephone speech in the presence of babble noise

Two procedures for improving the intelligibility of wideband telephone speech in the presence of competing babble noise are evaluated. One procedure is differentiation, the other consists of equalizing the speech spectrum by applying the inverse of the average spectrum of formant amplitudes for adult male speakers ("formant equalization"). Speech processed by these two methods was evaluated both for intelligibility and for listener preference. Both methods produced a clear increase in intelligibility compared to unprocessed wideband telephone speech. Formant equalization was found to be preferred over differentiation, more so at low signal-to-noise ratios than at high ones. (C) 2010 Acoustical Society of America. [DOI: 10.1121/1.3263603]