How does vocal-cord vibration affect the pitch of a voice?

In phonetics, the pitch of a voice is determined by the fundamental frequency of vocal-cord vibration, which corresponds to the number of air pulses—or cycles—produced per second, measured in hertz (Hz).12

The rate of these vibrations is influenced by several key factors:

• Vocal Cord Tension: The primary mechanism for adjusting pitch is the tension of the vocal cords. Increased tension, controlled by the cricothyroid muscle, results in a higher frequency of vibration and thus a higher pitch.2
• Glottal Resistance and Air Pressure: The force with which the vocal cords are held together (glottal closure) and the pressure of the air expelled from the lungs (subglottic pressure) also play significant roles. Higher expiratory effort and increased glottal resistance can contribute to higher pitch under certain conditions.23
• Laryngeal Dimensions: The physical size of the larynx acts as a stable determinant of an individual's pitch range. Generally, a smaller larynx produces a higher pitch range, which is why pitch varies based on age, sex, and body type.2

Essentially, lower-pitched sounds involve fewer cycles per second, while higher-pitched sounds require a much greater number of cycles.23