AN ACOUSTIC LANGUAGE UNIVERSAL: PERCEPTUAL EXPERIMENTS EMPLOYING NOISE-VOCODED SPEECH
AbstractA consistent clustering of frequency bands in different languages and dialects, i.e., English,French, German, Japanese, Mandarin, and Cantonese, had been found through factoranalyses applied to power fluctuations of critical-band filtered speech sounds [Ueda &Nakajima, Trans. Tech. Comm. Psychol. Physiol. Acoust., 38, 771-776, (2008); 39, 211-216,(2009)]. Four frequency bands appeared commonly to these languages and dialects. Theperceptual importance of these frequency bands were, however, largely unknown. We report aseries of perceptual experiments, in which we employed Japanese noise-vocoded speech thatwas synthesized to reconstruct amplitude envelope patterns in some frequency bands oforiginal speech. Almost perfect sentence recognition was achieved without training by usingnoise-vocoded speech synthesized with the four frequency bands above mentioned. Therelative importance of power fluctuations in low frequency bands was revealed. Spectral levelpatterns averaged in time had a small but significant effect on the intelligibility. These resultsshed lights on the critical roles, in speech perception, of the power fluctuations in lowfrequency bands.