Importance of tonal envelope cues in Chinese speech recognition

Abstract

Temporal waveform envelope cues provide significant information for English speech recognition, and, when combined with lip reading, could produce near-perfect consonant identification performance [Van Tasell et al., 1152–1161 (1987)]. Tonal patterns are important for Chinese speech recognition and can be effectively conveyed by temporal envelope cues [D. H. Whalen and Y. Xu, Phonetics 49, 25–47 (1992)]. This study investigates whether tones can help Chinese-speaking listeners use envelope cues more effectively than English listeners. The speech envelope was extracted from broad frequency bands and used to modulate a noise of the same bandwidth. Mandarin vowels, consonants, tones, and sentences were identified by ten native Chinese-speaking listeners with 1, 2, 3, and 4 noise bands (or channels). The results showed that recognition of vowels, consonants and sentences increases dramatically with the number of channels, a pattern similar to that observed in English speech recognition. However, tones were consistently recognized at about 80% correct level independent of the number of channels. This high level of tone recognition produced a significant difference in open-set sentence recognition between Chinese (11%) and English (1%, p<0.01) for the one channel condition where no spectral information is available.