The pitch of the human singing voice is a direct result of the frequency at which the vocal folds vibrate, measured in Hertz (Hz). A singer produces a high note because their vocal folds are vibrating quickly. Conversely, achieving a low note requires the vocal folds to slow their rate of vibration significantly. The typical male bass voice, the lowest standard classification, usually extends down to about 73 Hz, corresponding to the note D2, though some professional singers can reach even lower.
The Anatomy of Low Pitch Production
The production of low-frequency sounds depends on specific muscular actions within the larynx, often called the voice box. To lower the pitch, the body primarily engages the thyroarytenoid (TA) muscles, which make up the bulk of the vocal folds themselves. When these muscles contract, they decrease the distance between the thyroid and arytenoid cartilages. This action causes the vocal folds to shorten, thicken, and become more relaxed.
The resulting mass and slackness of the folds allows them to vibrate much more slowly as air passes through the larynx. The thicker and shorter the vibrating edge, the lower the fundamental frequency produced. Air pressure from the lungs is still required to initiate and sustain this slow, heavy vibration. Without sufficient and steady airflow, the vocal folds cannot maintain the slow cycle needed for a consistent low pitch.
The Lowest Measurable Frequency
The lowest frequency a human has demonstrably produced and held as a pitched sound is far below the standard musical range. The lowest note officially recorded was G-7, measured at an incredibly low frequency of 0.189 Hz. This extreme sound, achieved by a professional bass singer, is eight octaves below the lowest G on a piano. Since the lowest note typically audible to the human ear is around 20 Hz, this record-holding frequency is in the infrasound range and inaudible.
The sound is not a typical musical tone but a measurable sonic frequency produced by the vocal apparatus. Standard professional bass singers usually bottom out around 65 Hz, or C2, which is the lowest C note on a standard piano. This measurable limit is therefore a scientific curiosity, distinct from a practical, musically useful note.
Specialized Techniques for Extreme Low Notes
The ability to produce notes far below the natural physiological limits of the modal voice relies on a specialized technique known as vocal fry, also called laryngealization or pulse register. This technique fundamentally alters the way the vocal folds vibrate. Instead of the smooth, wave-like motion of normal singing, vocal fry is characterized by an extremely loose glottal closure.
This loose closure allows air to pass through in distinct, irregular pulses, creating a creaky, popping, or rattling sound quality. Physically, the vocal folds become compressed, slack, and thick, vibrating in a chaotic and extremely slow pattern. This irregular vibration allows the frequency to drop into the sub-audible range. Some advanced vocalists also employ subharmonic singing, a technique that manipulates the overtone series to create the illusion of notes lower than the fundamental frequency being sung.