Which muscle contributes to lowering the pitch of the voice?

The thyroarytenoid muscle plays a significant role in lowering the pitch of the voice. This muscle is found within the vocal folds and its contraction shortens the vocal cords, which in turn lowers their natural frequency of vibration. When the vocal cords are shorter, they tend to vibrate more slowly, resulting in a deeper, lower pitch. The thyroarytenoid muscle can be thought of as a tensor and relaxer of the vocal folds, facilitating changes in pitch during phonation.

In contrast, the cricothyroid muscle is primarily responsible for increasing pitch by elongating the vocal cords when it contracts. The oblique arytenoid muscle assists in adducting the vocal folds but doesn't have a direct role in pitch regulation. The lateral cricoarytenoid muscle is also involved in adduction, contributing to vocal fold closure, but similarly does not lower pitch. Thus, the unique contraction pattern and anatomical function of the thyroarytenoid firmly associate it with lowering vocal pitch.