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2011
Conference Paper
Titel
Acoustic interaction between bilateral piriform fossae
Abstract
The piriform fossae form the bottom of the vocal tract and generate two spectral dips. Our previous study [Takemoto et al., J. Acoust. Soc. Am., 128, 3724-3738 (2010)] revealed that the occlusion of one fossa canceled one dip and changed the center-frequency and amplitude of the remaining dip. This indicated that acoustic interaction exists between the fossae. To examine the interaction in detail, a simple three-dimensional model of the vocal tract was developed and changes of pressure and particle velocity distribution within the vocal tract at the two dip frequencies were computed using the finite-difference time-domain method. As a result, the bilateral fossae resonated almost in reverse phase at the lower dip frequency and in phase at the higher dip frequency. A coupled two-oscillator system successfully accounted for frequency and phase characteristics of the two dips: Two normal vibration modes generate two dips. Sound intensity analysis revealed that acoustic cou pling between the fossae and vocal tract was weak at the lower dip frequency, while it was strong at the higher dip frequency. This would be a reason why the lower dip had smaller amplitude than the higher one.