What does increasing subglottal pressure do to fundamental frequency?

Increasing subglottal pressure leads to an increase in fundamental frequency because it affects the tension and vibration of the vocal folds. When subglottal pressure is elevated, more air pressure pushes up against the vocal folds from below, causing them to vibrate more rapidly. This rapid vibration results in a higher frequency of sound produced.

Higher pressure causes the vocal cords to be forced apart more frequently during each cycle of vibration, leading to a higher pitch. This principle is essential in understanding voice production and is particularly relevant in clinical settings where a speech-language pathologist may evaluate or treat voice disorders that involve control of pitch.

The other options reflect an incorrect understanding of the relationship between subglottal pressure and fundamental frequency, as they suggest either a decrease or no effect on frequency, which does not align with the physiological mechanisms of voice production.