Which muscle action contributes to decreasing pitch?

The action of tilting the thyroid backward and relaxing the vocal cords is indeed key in decreasing pitch. When the thyroid cartilage tilts backward, it allows the vocal folds (cords) to become longer and thinner. This elongation leads to a decrease in the tension on the vocal cords, which typically results in a lower pitch during phonation. Relaxation of the vocal folds also contributes to this effect, as less tension naturally yields a deeper tone.

In phonation, pitch is primarily influenced by the tension and length of the vocal folds. When the folds are relaxed and elongated due to the backward tilt of the thyroid, they vibrate at a lower frequency, creating a lower pitch sound. This physiological understanding of how the laryngeal muscles operate helps clarify why this specific action contributes effectively to decreasing pitch.

Other options pertain to different muscle actions that either maintain or increase the pitch rather than decrease it, thus distinguishing the effects of these various muscle movements in voice production.