Kong, Y.-Y. & Zeng, F.-G. (2006). Temporal and spectral cues in Mandarin tone recognition. Journal of the Acoustical Society of America, 120(5), 2830–2840.
Presentation: Roger
Summary: Hsiao-chien
This study is aimed to evaluate the envelope and the fine structure cues used in Mandarin tone recognition for improving current cochlear-implant performances in pitch perception since both temporal and spectral fine structures are not explicitly encoded in the current processing schemes. The authors examined four types of acoustic cues in each experimental condition; first, for temporal envelope cues, the authors used the noise vocoder type of processing to manipulate the relative distribution of temporal and spectral information in the speech stimuli. Second, additional frequency modulation is used to produce better Mandarin tone recognition. Third, for presenting only the spectral envelope information in the absence of harmonicity cues, the authors made use of naturally recorded and LPC-synthesized whispered speech. Finally, the stimuli were manipulated by using the residue of a 14-order LPC processing.
Results of the first experiment showed that tone recognition performance was superior to the other three conditions in both quiet and noisy environments when both periodicity and spectral cues were available. Detailed spectral information (32 frequency bands) was required to produce tone recognition performance close to the original stimuli. Increasing the number of frequency bands improved tonal recognition, and frequency modulation (FM) contributed better tonal recognition. Tone recognition scores with spectral envelope cues were significantly poorer than those obtained with harmonicity cues alone in quiet and in all SNRs conditions. Overall, the present results are in agreement with previous studies of the effect of the number of bands. However, the authors found that temporal envelope cues are susceptible to noise, but spectral cues are more resistant to noise, which is considered a complementary contribution between temporal periodicity cues and spectral cues. This paper concluded that the fine structure had almost perfect performance than the envelope when observing the aspects of temporal and spectral cues. 
