How does the frequency of vocal-cord vibrations affect vocal pitch?

The frequency of vocal-cord vibrations is the primary determinant of vocal pitch. In physical terms, this frequency is measured in cycles per second, or Hertz (Hz), representing the number of air puffs produced as the vocal cords vibrate.1

The relationship between vibration and pitch is direct: a higher number of vibration cycles per second results in a higher pitch, while a lower number of cycles produces a lower pitch. For example, a low male voice may vibrate at approximately 100 cycles per second, whereas a high soprano note can reach 1,000 cycles per second.12

These vibrations occur as the glottis repeatedly opens and closes due to the interaction between subglottic air pressure and the resistance of the vocal cords. Within an individual's range, pitch is modulated by variables such as the tension of the vocal cords, the force of glottal closure, and expiratory air pressure. Increasing the tension of the cricothyroid muscle, for instance, raises the vocal pitch.21