Where does the voice come from?

The larynx (voice box) is a structure in the center of the neck that consists of several cartilages, the largest of which is the thyroid cartilage. In men, the Adam’s Apple actually represents the uppermost portion of the front of the voice box (this is difficult to feel in women). There are several groups of muscles inside the voice box framework that are responsible for altering the length, tension, shape and spatial position of the vocal cords, allowing them to open (to breath), close (to speak,
sing, cough) and stretch (to sing high notes).

The complex microanatomy of the true vocal cord allows the loose and pliable superficial layers to vibrate freely over the stiffer structural deeper layers – much like a sleeve can slide and rotate around your forearm. Vocal cords have three major layers: the mucosa (skin and connective tissue), the vocal ligament and the underlying muscle. The mucosa of the vocal fold is highly specialized for its vibratory function.

How does the voice work?

The voice box plays a role in breathing, swallowing and airway protection, but the most complex and highly specialized of the laryngeal (voice box) functions is sound production. The ability to couple phonation with articulation and resonance allows for human speech. Phonation and precisely how it relates to laryngeal vibration has undergone many evolving theories over the years. Sound production requires
that several mechanical properties be met. First, there must be adequate breath
support to produce sufficient pressure; secondly, there also must be adequate
control of the laryngeal musculature to produce not only vocal cord closure
but also the proper length and tension of the vocal folds. Finally, there must
be favorable pliability and vibratory capacity of the tissues of the vocal folds. Once these conditions are met, sound may be generated. As an analogy, the two vocal cords vibrate together as do one’s lips when blowing a “raspberry.”

Actual phonation is a complex and specialized process that involves not only brainstem reflexes and the laryngeal muscular actions, but highlevel cortical control as well. Accessory effects such as lung capacity, chest wall compliance, pharyngeal, nasal, oral anatomy and mental status also play a role. The process begins with inhalation and vocal cord closure. During exhalation, an increase in air pressure below the vocal cords follows until the pressure overcomes the closure force of the
vocal cords, and air is allowed to escape between the vocal cords. Once air passes between the vocal cords, the vocal cords come back together due to pressure changes and elastic recoil. This completes one “cycle” of vibration. As long as the airstream continues, the cycle repeats itself at a rapid rate. At a normal male speaking frequency, the cycle is occurring approximately 100-120 times per second; and at a normal female speaking frequency, 200-230 times per second. In singers, the higher the note, the faster the cycle frequency. To reach notes in the high soprano range, one might be asking their vocal cords to vibrate more than 800 or 900 times per second. So, don’t forget to give your voice a break – it’s working hard for you!