Predictions of fundamental frequency changes during phonation based on a biomechanical model of the vocal fold lamina propria.

This study examines the local and global changes of fundamental frequency (F(0)) during phonation and proposes a biomechanical model of predictions of F(0) contours based on the mechanics of vibration of vocal fold lamina propria. The biomechanical model integrates the constitutive description of the tissue mechanical response with a structural model of beam vibration. The constitutive model accounts for the nonlinear and time-dependent response of the vocal fold cover and the vocal ligament. The structural model of the vocal fold lamina propria is based on a composite beam model with axial stress. Results show that local fluctuations such as F(0) overshoots and undershoots can be characterized by the biomechanical model and might be related to the processes of stress relaxation of vocal fold tissues during length changes. The global changes of F(0) declination in declarative sentence production can also be characterized by the model. Such F(0) declination is partially attributed to the peak stress decay associated with stress relaxation of the vocal fold lamina propria and partially to neuromuscular control of the vocal fold length.