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Abstracts & Full Papers
289 - The tuning of vocal tract resonances in singing and in playing the didjeridu
Smith J., Wolfe J.
Abstract
The different vowel sounds in normal speech are produced by adjusting the position of tongue, lips and teeth so that the vocal tract resonates at certain specific frequencies. In voiced speech, these resonances interact with the harmonics of the signal from the vibrating vocal folds to produce associated peaks, or formants, in the output spectrum. For singers, the use of these resonances is sometimes constrained more by musical than linguistic context. For sopranos, the vibration frequency of their vocal folds may be much higher than the normal values for the lowest resonance, and consequently a reduced interaction would cause a loss of power. Direct measurements of the resonance frequencies of the vocal tract of classically-trained sopranos during singing show that they consistently increase them to match the frequency of their singing. This significantly increases the loudness and the uniformity of tone, at the expense of comprehensibility. The fundamental frequency of other singers is usually less than the value of the lowest resonance so they gain less by tuning this resonance. However the power may be increased by tuning the resonance frequency to a harmonic of the fundamental frequency. Our measurements indeed show that some altos, tenors and baritones use this strategy when appropriate. The role of the vocal tract resonances is quite different when playing the didjeridu or yidaki. The sound is then primarily generated by the vibrating lips, although the vibrating vocal folds are also sometimes used for various effects. The frequency of vibration is then primarily determined by one of the strong resonances of the wind instrument itself. Our measurements show how varying the resonances of the vocal tract can change the harmonic structure or timbre of the produced sound. The described research has involved several members and associates of our Acoustics Laboratory.
Citation
Smith J.; Wolfe J.: The tuning of vocal tract resonances in singing and in playing the didjeridu, CD-ROM Proceedings of the Thirtheenth International Congress on Sound and Vibration (ICSV13), July 2-6, 2006, Vienna, Austria, Eds.: Eberhardsteiner, J.; Mang, H.A.; Waubke, H., Publisher: Vienna University of Technology, Austria, ISBN: 3-9501554-5-7