The cricothyroid muscle is an important muscle in the human larynx, which is closely related to vocal cord movement. When the cricothyroid muscle contracts, it can tighten and lengthen the vocal cords. Vocal cords are two elastic tissues located in the throat. When air passes through the glottis, the vocal cords vibrate to produce sound. The contraction of cricothyroid muscle can change the tension of vocal cords, and then affect the vibration frequency and pitch of vocal cords. Specifically, the contraction of the cricothyroid muscle will lengthen the vocal cords, increase their tension, and make the vocal cords more tense. Nervousness helps to produce higher-pitched sounds. The contraction of cricothyroid muscle is regulated by the movement control center of throat. When treble is needed, the central nervous system will send a signal to stimulate the cricothyroid muscle to contract, thus lengthening the vocal cords and producing higher tones.