Control of chaotic vibrations in lumped mass models of the vocal folds

Abstract

Lumped mass models have been widely used as low-dimensional systems to better understand the physics underlying human phonation. This is a highly non-linear process in which subglottal flow emanating from the lungs excite self-oscillations of the vocal folds. Consequently, a pulsating volume velocity is established that produces acoustic waves, which then travel through the vocal tract and are released from the mouth as voice. The self-oscillations of the vocal folds may be affected by many undesirable factors like the presence of polyps, lateral paralyses, excessive subglottal pressure, etc., and transition from regular to chaotic motion. This gives rise to abnormal phonation. In this work, we explore the theoretical possibility of adding smart materials to vocal fold lumped mass models. The smart material must be such that its damping can be dynamically modified. By proper tuning, one can establish a feedback control mechanism that restores chaotic vocal fold oscillations to normality. This would constitute the essence of a pacemaker for phonation.