15th Annual Conference of the International Speech Communication Association

September 14-18, 2014

Comparison of Vocal Tract Transfer Functions Calculated Using One-Dimensional and Three-Dimensional Acoustic Simulation Methods

Hironori Takemoto (1), Parham Mokhtari (1), Tatsuya Kitamura (2)

(1) NICT, Japan
(2) Konan University, Japan

Acoustic characteristics of the vocal tract have been investigated extensively in the literature using a one-dimensional (1D) acoustic simulation method. Because the 1D method assumes plane wave propagation only, it is recognized to be valid only in the low frequency region (below about 4 or 5 kHz). Recently, a three-dimensional (3D) acoustic simulation method was developed, to obtain more precise acoustic characteristics of the vocal tract. In the present study, from a male's vocal tract shapes, transfer functions were calculated using the 1D and 3D methods and compared with each other to evaluate the valid frequency range of the 1D method. As a result, when acoustic effects of the piriform fossae were considered in the 1D method, the transfer functions agreed with each other up to 7 kHz (ignoring small dips). The 3D method showed that a deep dip was generated at around 8 kHz by the transverse resonance mode in the pharynx. Above this dip frequency, the transfer functions disagreed with each other. Thus, the 1D method is valid up to 7 kHz for this subject. Because this subject has a relatively large vocal tract, in general the upper limit of the valid frequency range could exceed 8 kHz.

Full Paper

Bibliographic reference.  Takemoto, Hironori / Mokhtari, Parham / Kitamura, Tatsuya (2014): "Comparison of vocal tract transfer functions calculated using one-dimensional and three-dimensional acoustic simulation methods", In INTERSPEECH-2014, 408-412.