| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 99 === We often heard erhu performers or makers use the term “sweet” to describe the timbre of erhu, but how this judgment is made is quite arbitrary; that is, there is no objective criteria for the sweetness of timbre. Therefore, this study performed subjective evaluation and objective quantitative analysis on the “sweetness” of the timbre of erhu in order to verify the four major factors affecting the sweetness of timbre.
Subjectively, sweet timbre should possess a high proportion of consonant component. The authors calculated the consonant and the dissonant components for each monotone based on the consonant and the dissonant relationship between fundamental frequency and overtones. By calculating the acquired harmonic components, the study verified that subjective evaluation was in fact quite accurate. The second factor affecting the sweetness of erhu is the volume between 4,000 Hz and 16,000 Hz—in this range, the acoustic pressure of sweet timbre cannot be too high. If the volume is slightly higher between 4,000 Hz and 8,000 Hz, the timbre would be too bright. If the volume is slightly higher between 8,000 Hz and 12,000 Hz, then the timbre would be too sharp. Sweet timbre should be neither too bright nor too sharp.
In addition, purity and volume equilibrium of music indices are also related to sweetness as well. Purity is highly correlated with sweetness, and timbre perceived as sweet must be highly pure as well. As for volume, if the volume of one note is significantly different from the volume of another, then sweetness will be reduced. Results from the analysis suggest that these two music indices well support the subjective viewpoint.
In terms of the start-up and the decay time of the timbre of erhu, it is subjectively considered that sweet timbre should have a shorter start-up time, while the decay of sweet timbre should be relatively slower. Our data here verified that the overall damping of sweet timbre of erhu is indeed smaller, and this is consistent with subjective assessment.
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