Computer model to characterize the air volume displaced by the vibrating vocal cords

Abstract

A vocal-cord/vocal-tract model devised earlier to study acoustic effects of the air volume displaced by the vibrating vocal cords [humans] was used. Lateral and longitudinal motion of the cords was considered. Computer simulations were made to establish quantitatively the contribution of the displacement current to the total glottal volume velocity (and hence to the total sound excitation for voiced sounds). The displacement current from lateral and logitudinal motion was found to be 2nd-order by comparison to the total glottal flow. The displacement contribution could be identified in the time waveforms and spectra of the glottal and mouth volume velocities. The computer formulation was used to synthesize speech sounds with and without the displacement current. Auditory observations and spectral calculations on the synthetic output show the displacement current to be discriminable only in close differential comparisons.