What is phonation? Definition and examples

While the use of this term can vary within different fields and disciplines, phonation fundamentally describes the body’s use of air in the production of vocal sounds – especially speech, but including singing, humming, growling, moaning, and so on. 

This physiological process involves several parts of the body working in concert:

• The lungs 
• The larynx (or voicebox): an organ in the neck also involved in respiration and in protecting the windpipe (trachea) against the inhalation of food or liquid (aspiration) 
• The vocal folds (formerly known, inaccurately, as vocal cords): two bands of pearly white tissue covered by mucous membrane and housed within the larynx which open when we breathe in or out, and which are connected to a variety of muscles and cartilage
• The throat, mouth, and tongue.

When exhaled from the lungs – and therefore provided by the respiratory system – air passes through the larynx, causing the vocal folds to vibrate. The folds may vibrate hundreds of times per second, depending on the pitch of an individual’s voice. The buzzing acoustic energy that this creates (called ‘voice’) is the basis of speech. If the larynx were to “operate without any of the resonating areas above it (i.e. without your head!), the sound made by the vibrating folds would be similar to a ‘raspberry’ made with the lips, or perhaps a duck call”. Air pressure below the larynx must be sufficient to blow the vocal folds apart, meaning that, by passing through the glottis (the opening between the vocal folds), the vocal folds open and close rapidly, breaking the airflow into bursts of sound waves. This gives us pitch and volume – then, when the air reaches the vocal tract (muscles in the mouth and throat that filter sound), this, combined manipulation by the sinuses, tongue, teeth, and soft and hard palates, create individual sounds, fine-tuning their sound quality and volume; these are the results of “the articulatory actions of the […] vocal apparatus”. Once combined, this is what shapes the recognizable sounds we recognise as speech. 

As such, phonation is reliant on co-ordination between the respiratory and laryngeal systems. It also developed as a by-product of the larynx’s primary respiratory and protective functions; “a versatile secondary capacity to exploit the laryngeal apparatus for making and controlling sound through phonation”.

Different vocal sounds, textures, and qualities (like hoarseness, breathiness, roughness, raspiness, voice breaks, and pitch breaks) can be made by variations in how air is released through the larynx and how tightly the vocal folds are held. For example, the low creak or rattle of vocal (or glottal) fry, comes about by allowing the vocal folds to vibrate at a very low frequency by relaxing them. Pitch, then – our perception of how high or low a sound is – is related to the speed at which the vocal folds are vibrated (see also our entry on frequency). Fast vibrations create higher tension and higher pitches; slow vibrations create lower tension and lower pitches. However, the vocal folds’ thickness and length is also significant to how high or low one’s voice is, with thicker folds equating to a lower pitch and therefore a deep voice; accordingly, men typically have thicker vocal folds than woman.

It is also possible to create sounds separate from the phonation process. Whereas ‘voiced’ sounds are produced through phonation, ‘unvoiced’ sounds do not – meaning that vibration of the vocal folds is not necessary to produce them; these include hissing and whispering. The latter is produced by vocal folds being held rigid and slightly apart; this means that they don’t vibrate and allow turbulent air to pass through the glottis.

However, the larynx’s muscles “work ‘involuntarily’ […] through a biofeedback process involving sensing and monitoring the vibration of the vocal folds through the sound and feeling it creates”. For this reason, it may take a lifetime to learn how to make conscious adjustments to these actions.

---

Featured photo by Denis Sebastian Tamas on Unsplash