Complementary contributions of spectral and temporal cues

Abstract Nearly perfect speech recognition under condition of severe reduction of spectral information has been observed with using noise-vocoding technique. This finding suggested the utilization temporal envelope to recognize speech sound. In this study, the resolutions of spectral and temporal information were systematically varied to assess contribution of temporal envelope to the sentence intelligibility in detail. The number of spectral band was changed from 4 to 16. The temporal envelope was smoothed by low-pass filter with a variation of cutoff frequency from 2 to 16 Hz. The results showed that the smoothness of temporal envelope highly affected sentence intelligibility rather than spectral resolution for the range of the experimental condition. Moreover, the slowly varying components between 2 to 8 Hz within temporal envelope contributed to recognition speech on the condition severely degraded in spectral information