元音和复合音识别中噪音分离机制的实验研究

Harmonicity is one of the important features of a vowel. It makes great contribution to pitch and quality of vowel. However, contribution of a mistuned harmonic will decrease as it is mistuned increasingly. A mistuned harmonic will be segregated as noise from complex by auditory system, which was called harmonic sieve (Duifhuis, 1982). According to Darwin (1986) and Moore et al (1985), the critical value of one mistuned harmonic would be segregated from vowel or complex is 3% to 8%－－Harmonic Mistuned Effect (HME). Further questions need to be answered. For example, how will the harmonic sieve separate noise or whether the critical value change when more than two harmonics are mistuned? And what affect the HME? Three experiments were conducted to these questions. Experiment one was dealt with the number of mistuned harmonics as a factor affecting the HME. The position effect of HME was concerned in experiment two. The last experiment considered the relationship between HME and phase of the mistuned harmonic. The results indicated that (1) the HME was much greater when more than two harmonics were mistuned than only one harmonic was mistuned; (2) harmonic position played an important role in HME, the higher the harmonic was, the less HME was found for the complex, and the closer to formant the harmonic stood, the more significant HME existed; and (3) phase did not affect the HME significantly, however, its indirect contribution still existed, which related to the starting amplitude of a mistuned harmonic.