A model for vocal cord excitation.

This paper reports the results of an experimental and analytical investigation of a possible mechanism for exciting vibrations of the vocal cords. In order to test various approximations for describing the flow past the vocal cords and to demonstrate the importance of the upstream impedance in the excitation mechanism, the vocal cords are first represented by the simplest possible model, namely a simple vibrator of fixed shape. It is shown that if the pressures at the upstream and downstream ends of the channel formed by the vibrator wall are constant, the aerodynamic forces take energy from the vibrational motion. If, on the other hand, the output impedance of the system upstream of the channel is negative imaginary, vibrations of the channel walls can be excited. Experimental results agree with the predictions of the flow analysis for the simple vibrator. It is then argued that the respiratory system upstream of the larynx can be described as a tube 20 cm long in which the wave speed is reduced because ...