Effects of electrical stimulation of cricothyroid and thyroarytenoid muscles on voice fundamental frequency

Voice pitch depends on the interaction of several variables, including contraction of laryngeal muscles and respiratory events. It is difficult to parcel out the contributions made by specific laryngeal muscles, since muscles normally co-contract. Moreover, the contraction speed of human laryngeal muscles has not been determined. In order to better understand these phenomena, stainless steel electrode wires were inserted into the cricothyroid and thyroarytenoid muscles of normal subjects, and during phonation, single, low-voltage shocks were delivered to one muscle. The frequency of shock presentation was varied from 1 to 90/s. The results show that both muscles cause elevation of voice pitch. The thyroarytenoid has a faster contraction speed than the cricothyroid.