EFFECTS OF FREQUENCY-BAND ELIMINATION ON SYLLABLE IDENTIFICATION OF JAPANESE NOISE-VOCODED SPEECH: ANALYSES OF CONFUSION MATRICES
We accomplished factor analyses on power fluctuations of speech signals, filtered through a critical-band filter bank, in Chinese (Cantonese and Mandarin), English (American and British), French, German, Japanese, and Spanish uttered by 10-20 native speakers. Speech information can be well conveyed through power fluctuations in four frequency bands common to all these languages and dialects. The effects of eliminating one of the frequency bands on Japanese syllable identification were observed, to specify the roles of each frequency band in speech perception, by using noise-vocoded speech stimuli. The elim- ination of one of the two lower bands caused most severe deterioration in identification. Specifically, the elimination of the lowest band tended to increase frequency of response misidentifying voiced consonants as voiceless consonants. Thus, even in stimuli without periodicity, power fluctuations in the lowest frequency band affects voiced vs. voiceless distinction of speech.