Phonation

neat stuff done by the vocal folds

Anatomy

The vocal folds (or cords) are two flaps of tissue attached to the cartilages of the larynx (or voicebox). Muscles can move the cartilages in order to adjust the position and tension of the vocal folds.

vocal folds from above - diagram vocal folds from above - photo

Glottal states / Types of phonation

We've been acting as if only one question mattered: are the vocal fold vibrating or not? Segments with vocal fold vibration are voiced, all others are voiceless.

There's more than one way the vocal folds can vibrate. There's more than one way they can fail to vibrate.

Not vibrating

Glottal stop

The vocal folds are held together without vibrating. No air escapes from the lungs.

Open breathing

The vocal folds pulled as far apart as possible -- no sound.

Voiceless

The vocal folds are too far apart to vibrate, but close enough that they can cause some turbulence in the airstream under the right circumstances. (This is what "voiceless" usually means.)

Whisper

Vibrating

Modal voicing

The vocal folds are held together along their full length with enough tension to allow vibration:

The vocal folds momentarily block airflow from the lungs.
The air pressure underneath the vocal folds increases.
The increased pressure forces the vocal folds up and apart.
As the pressure falls again, the vocal folds snap back together.
Go to 1.

Each repetition of this cycle causes a "glottal pulse". The number of times this occurs in a second is the fundamental frequency of voice.

Varying the tension of the vocal folds results in different rates of vibration (and so different pitches).

Breathy voice (or murmur)

The vocal cords are vibrating, but there is also a significant amount of air escaping through the glottis, causing turbulence.

Creaky voice

In creak, only the front part of the vocal folds are vibrating, giving a very low frequency. (Try speaking at the lowest pitch you can. Then go even lower.)

The very low frequency vibration of creak can be superimposed on modal voicing, producing creaky voice.

Creak and creaky voice are often called "laryngealization" or "vocal fry".

Falsetto

The vocal folds are stretched tightly so that they become very thin. The resulting vibrations can have over twice the frequency that a speaker can produce using modal voicing.

Combinations

Various combinations of the above are possible. For example, you can get a creaky falsetto by superimposing creak onto falsetto voicing rather than modal voicing (think Grover on Sesame Street).

Non-linguistic uses of voice quality

People may use different types of phonation in different situations, either consciously or unconsciously (e.g., whisper when telling a secret, breathy voice when excited, creaky voice during a hangover).

A person's tendency to use various (combinations of) types of phonation is one of the most important things that makes their voice "theirs".

People who need to talk in two or more different identifiable voices (e.g., puppeteers) will usually use different phonation types for the different voices.

Speech/language pathologists usually make a distinction between

articulation disorders
voice disorders (problems with phonation)

roughly the distinction between filter and source. The goal of much therapy is to help the client gain an appropriate use of modal voicing.

("Voice quality" is often also used to describe aspects of the filter, specifically vocal tract "settings" that persist over a stretch of speech. For example, if the average position of the tongue body during an utterance is markedly higher and further forward than it normally is in the speech community, some people will say that the utterance has "palatalized voice".)

Transcribing

The "Extended IPA" offers ways of transcribing voice quality. Stretches of speech with a particular voice quality can be marked with curly braces. The braces are labelled with a symbol for the voice quality, for example:

transcription with breathy voice

Linguistic uses of voice quality

Moving into a different phonation type (especially creaky voice) can help signal parenthetical comments:

The phonetics course { which is really interesting } is almost over.

Ordinary voiceless phonation (sometimes whisper) can be used to produce voiceless vowels and [h].

Many languages use the glottal stop phonation by itself, treating it as a segment. (Phonological "glottal stops" are often realized with creak or creaky voice instead.)

Phonation types can create contrasts between segments. Deviations from ordinary voicelessness or modal voicing are marked with diacritic symbols.

E.g., contrasts between:

a vowel with modal voicing
a vowel with breathy or creaky voicing

a voiceless aspirated stop
a "voiced aspirated" stop, i.e., a stop with breathy voice phonation. After the release of the stop, the breathy voice continues for an interval before the onset of modal voicing (parallel to the lag in Voice Onset Time in voiceless aspirated stops).

Different pitches of modal voicing can be used in tone languages to create contrasts between segments. We've already seen the uses of different pitch in the suprasegmental system of English.

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