Study of the Effect of a Moderate Asymmetry on a Replica of the Vocal Folds

Studies of vocal fold asymmetries have received attention by researchers for numerous causes. Means to study actual vocal folds with measurable asymmetries have heretofore been limited. We present a vocal fold replica with controllable and measurable asymmetries between the two folds. Using this set-up we indeed observe a measurable effect of the mechanical asymmetry on critical output parameters such as the threshold pressure and the sound intensity. We examine whether a lumped mass model of vocal fold dynamics behaves similarly to the replica, within the limits of the model. We find that certain phenomena, such as phonation onset pressure and spectral intensity, are quite similar within a neighborhood of perfect symmetry, while fundamental frequency changes consistently with the asymmetry.