Which muscle is primarily responsible for changing the pitch of the voice?

The cricothyroid muscle plays a crucial role in modulating the pitch of the voice. It achieves this by adjusting the tension of the vocal cords, which directly affects their vibratory frequency. When the cricothyroid muscle contracts, it causes the thyroid and cricoid cartilages to tilt relative to each other, thereby lengthening and tightening the vocal folds. This increase in tension enables the folds to vibrate at higher frequencies, producing higher pitches. Conversely, when the muscle relaxes, the tension decreases, leading to lower frequencies and pitches.

Understanding the function of the other muscles is also important. The thyroarytenoid muscle primarily makes the vocal folds thicker and more relaxed, which can lower the pitch rather than raise it, whereas the transverse and oblique arytenoid muscles are involved in the adduction of the vocal folds, helping them come together for vocalization but not specifically in pitch adjustment. Therefore, the cricothyroid is the most critical muscle for changing the pitch of the voice.