Vocal wow in an adapted reflex resonance model

Abstract: Vocal wow is a slow 0.2 - 3 Hz modulation of the voice that may be distinguished from the 4 - 7 Hz modulation of tremor or vibrato. We use a simple model of laryngeal muscle activation, mediated by time-delayed auditory feedback, to show that wow may arise due to Andronov-Hopf bifurcation. The model demonstrates a differential effect of feedback gain and delay on modulation depth and frequency, respectively. Parametric formulas for recovering feedback parameters from the acoustic signal are presented. Interactions between reflex and auditory parameters are also assessed in a full model that includes a neuromuscular reflex loop. Model predictions are tested in two subjects