The role of the larynx Phonetics chapter 2 - PowerPoint Presentation

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The role of the larynx

Phonetics chapter 2

What is the Larynx?

The larynx is a box made of cartilages, inside this box the vocal folds which are two thick flaps of a muscle rather like a pair of lips.

The front wall is the

thyroid

cartilage

, or ‘shield cartilage’ , responsible for the ‘Adam’s apple’ (the thyroid prominence) and which is located at the front of the neck.

Behind the thyroid prominence, on the inner surface of the cartilage is the anchor point for the front ends of the

vocal

folds

.

The thyroid cartilage is located at the top of the trachea (wind pipe) and controls the flow of air.

The very top cartilage is a complete circle and is known as the cricoid cartilage or ‘ring cartilage’

The Vocal Folds

The vocal folds are fleshy folds of tissue, they are attached at the front

like the

thyroid cartilage and are effectively hung like a pair of very substantial curtains across from the front to back of this structure.

Muscles

attaching to the

aretynoid

cartilages are the main force for positioning the folds in an open (abducted) or closed (adducted) position. When open, the space between the folds is called the glottis.

The

egressive

pulmonic

airstream:

The larynx or The

interaction between the vocal folds and the

egressive

pulmonic

airstream, is

responsible for phonation, the sound source which is termed voice in speech

.

Various airstreams are used in speech but the basic one is the

egressive

(moving outwards) pulmonic( from the lungs) airstream.

Sounds can’t be produced without air coming from the lungs.

The airstream comes from the lungs and goes the vocal tract

The vocal tract consists of: the trachea, the larynx,

supraglottal

cavities (the cavities above the glottis), the pharynx, the oral cavity, and the nasal cavity.

The process of speaking (producing sounds)

When we speak, we first inhale, filling the lungs with air, and then we engage in something reminiscent of what swimmers call “trickle breathing”.

We expel the air in a carefully controlled fashion at a rather slower rate if we were just breathing out for normal breathing. This maximizes the air and allows us to speak for some time without needing to breathe in again.

The expulsion is controlled or regulated by the action of muscles moving the diaphragm and by the various pairs of muscles that act on the rib cage.

The pathway (for the airstream) is thus:

Out from the lungs

Up the trachea

Via the larynx

Into

supraglottal

cavities( the cavities above the glottis : the pharynx(the throat), the oral cavity(the mouth) and the nasal cavity ( the nose) which also form the vocal tract.

Normal Voice

Normal, chest or modal

voice is the result of the vocal folds vibrating in a particular way.

This happens, as soon as the speaker has inhaled, the

aretynoid

cartilages draw the folds (and themselves) together, then they are opened by the pressure of air which is expelled from the lungs, which is strong enough to push the vocal fold apart to produce voice

.

The effort being made by the

aretynoid

is strong enough to enable the folds to close again.

They repeat on average 100–120 times per second for adult male voices and 200–240 times per second for adult female voices. In children, it can be 300 times per second.

We hear this as pitch when we listen to speech, and deliberately varying the rate of vibration of our vocal folds makes our voices go up and down in pitch, adding intonation.

Basically, the faster the rate of vibration, the higher the pitch of the voice.

Elastic recoil brings the bottom edges back together and then the effect passes up the folds to the top, bringing them back together in depth.

This is a complex process- the pressure drop means there is also a small suction effect known as ( Bernoulli effect).

Creaky voice/ Vocal, Glottal Fry/

It is the result of an extremely low pitch voice.

For some speakers of English, creaky voice is part of their idiolect.

Some speakers tend to cultivate a very ‘creaky’ way of speaking, female speakers of American English.

Americans refer to this sound as glottal fry and the quality is sometimes an indicator of social status.

The big differences between creaky voice and normal voice are that the vibratory cycles tend to be irregularly spaced in creaky as opposed to regular in normal voice and that the frequency is always very low

.

It could be found in a speech of a female speaker of American English.

Creaky voice is used in some African dialects to distinguish meanings of words

Similarly, creaky voice is also used in Danish where it is responsible for the linguistic characteristic known as

stød

in which a short interval of creaky voice affects the end of certain longer vowel sounds or sonorant consonants when they follow shorter vowels.

Sonorant consonants are typically those which appear as ‘voiced only’ entries in the IPA chart (m-sounds, n-sounds, l-sounds, vowels, etc.).

Breathy voice

Whispering and sighing are forms of breathiness, but these are also voiceless.

To achieve this effect, the

aretynoids

draw the folds together, closing the folds themselves firmly, so that they resist the pressure from the

egressive

pulmonic

airstream, but maintaining a gap between the two cartilages to enable the air to escape continuously at this point.

Breathy voice is produced when the closure of the folds is less firm and the airstream not only escapes continuously between the open

aretynoids

,

but also sets the folds vibrating

It is mostly used in/h/ sound and when someone is out of breath.

THE LARYNX AS A PLACE OF ARTICULATION

The glottis can be a place of articulation as well

sounds made by the glottis are called

glottal

/h

/.

To produce this voiceless variant, a different setting is required in which the folds and

aretynoids

are drawn near to each other, but not touching, leaving a very small space between them such that as the

egressive

pulmonic

air forces its way through, it becomes turbulent or ‘disordered’ and makes an h-sound.

Another sound is produced in the larynx, is the

glottal stop [ʔ]

found in London

Englishes

mostly known as

t-

glottalling

THE LARYNX AS A PITCH MODULATOR

Lexical use of pitch: there are many languages that use pitch to make distinctions in meanings of words, these known as tone languages.

In a language like English, pitch changes map over a longer phrase (called the

intonational

phrase). Here, a falling tone \

car

gives the listener the impression of a statement (it is a car) while a rising tone /

car

is more likely to be interpreted as a question (is it a car?).

The same syllable spoken with a mid tone >car sounds as if the utterance is incomplete (maybe the speaker forgot what they were going to say next), and so on.

VOICE AND THE IPA CHART