Acoustic properties for the distinction of Japanese stop consonants

Of all the sounds of speech. stop consonants present the greatest obstacles to automatic speech recognition. A study has been conducted to find acoustic properties that can be exploited for reliable distinction among the stop consonants of Japanese in CV utterances produced by five male speakers of Japanese. Short-time spectra were measured at the stop burst and at the onset of the following vowel. It was found that the most consistent property for distinguishing velar stops from other consonants is the presence of a dominant peak in the burst spectrum in the vicinity of the second/third formant of the following back/front vowel. On the other hand, the distinction between alveolar and labial stops can be made on the basis of the second formant transition when the stops are followed by a back vowel. This transition is concave for alveolars and almost level or convex for labials. When these stops are followed by a front vowel, however, the overall slope of the burst spectrum can be more reliably used for their distinction than the second formant transition. A similar analysis was also made on the nasal consonants of Japanese. [Work conducted at Research Laboratory of Electronics, Massachusetts Institute of Technology while the author was on leave from University of Tokyo.]