Airstream mechanisms

 

Intelligible sounds are produced by firstly placing the organs of the vocal tract in a specific configuration which influences the flow of air as it passes through the oral and/or nasal cavity.

To produce a distinctive speech sound, there are two requirements:

i. a configuration of organs

ii. a flow of air or airstream

How are airstreams initiated or provoked?

Basically, the questions to be answered regarding the airstream in the production of most speech sounds are two:

1. Is the airstream pulmonic or non-pulmonic?

2. In the production of sounds, does the air flow out of the body or is the air drawn into the body?

All speech sounds are produced on a moving airstream.

The organs which can provoke or initiate the movement of the air in the vocal tract are called "initiators".

There are three initiators:

- the lungs

- the vocal folds (glottis)

- the tongue

initiator (type of airstream)

egressive

ingressive

1. lungs

most speech sounds of

Indo-European languages

inhaled sigh

2. glottis

(glottalic or pharyngeal)

ejectives

(unvoiced)

implosives

(slightly voiced

3. tongue

spitting

clicks

(primary articulation)

 

 An airstream initiated by the lungs is called a pulmonic airstream.

An airstream initiated by the glottis is called a glottalic airstream.

An airstream initiated by the tongue is called a velaric airstream.

Most speech sounds used by Indo-European language speakers are produced on a pulmonic and egressive airstream.

A pulmonic egressive airstream is used to produce a speech gesture known as an inhaled sigh.

Both egressive and ingressive glottalic airstreams are used to produce speech sounds.

Speech sounds produced on a glottalic egressive airstream are called "ejectives".

Speech sounds produced on a glottalic ingressive airsatreams are called "implosives".

The velaric egressive airstream produces a speech getsure known as "spitting".

The velaric ingressive airstream produces speech sounds known as "clicks" which occur in double articulations in some African languages, for example, Xhosa.

Certain clicks, for example, the dental click, are universalised speech gestures, cf. the dental click - tut-tut - and "the kiss" /  / and the lateral click - "gee-up" - to make a horse move.

 

Pulmonic sounds

a. Pulmonic egressive

During the natural process of exhalation, the lungs act as initiators of an airstream.

The diaphragm is raised by muscular action, causing the lungs to contract.

The subsequent reduction of lung capacity forces air out of the lungs, up the trachea through the vocal folds and out of the body through the nasal and / or oral cavity.

b. Pulmonic ingressive

During the natural inhalation process, the diaphragm is lowered by muscular action, causing an increase in lung capacity.

The subsequent decrease in air pressure in the vocal tract and lungs causes air to be drawn into the body in order to compensate for the decrease in air pressure.

The inhaled air passes between the lips, through the oral cavity - or alternatively through the nasal cavity - down the trachea, through the vocal folds to the lungs.

The inhaled airstream is not normally used in the production of speech sounds, since the air must pass through wide open vocal folds in order to reach the lungs.

The only sound which is frequently made on the inhaled pulmonic airstream is the inhaled sigh.

 

Glottalic sounds

Glottalic sounds are produced by closing the vocal folds tightly shut so that no air can pass through the glottis.

Then, by muscular action of the larynx, the glottis is moved either up or down, initiating an egressive or ingressive airstream respectively.

a. Glottalic egressive (ejectives)

Ejectives are produced on a glottalic egressive airstream.

By muscular action, the closed glottis is moved upwards, forcing air out of the oral or the nasal cavity.

The upward movement of the glottis causes the air in the trachea and oral cavity to be pushed with force out of the mouth or nasal cavities.

All ejective speech sounds are accompanied by heavy aspiration.

Since no air can pass through the tightly closed vocal folds, all ejectives are unvoiced.

Ejectives:

plosives []; []; []

fricative []; []

affricate []; []

Example:

// (Xhosa) meaning father

cf. // (Xhosa)

All ejectives are unvoiced and they are all heavily aspirated.

 

b. Glottalic ingressive (implosives)

Implosives are produced on a glottalic ingressive airstream.

The glottis is closed tightly.

By muscular effort of the larynx the glottis is moved downwards in the trachea.

The downward movement of the glottis causes a decrease in air pressure in the supraglottal cavities - the top of the trachea, oral and/or nasal cavities.

Subsequently, in order to compensate for the the decrease in supraglottal air pressure, air rushes into the body between open lips and through the oral cavity or alternatively, in through the nasal cavities, down the trachea and then on between slightly open vocal folds.

Since the articulators in the oral cavity must form an airtight closure in order that rarefication occurs when the tightly closed glottis is lowered, all speech sounds produced on a glottalic ingressive airstream are stops or (im)plosive sounds.

Following the articulation of implosives, the vocal folds relax so that some air passes through them causing slight voicing.

Implosives:

bilabial - []

alveolar - []

velar - []

Example:

/ / meaning count (Xhosa)

cf. // meaning write (Xhosa)

 

Velaric or oral sounds

Velaric sounds are produced on an airstream initiated by the tongue.

a. Velaric egressive

The velaric egressive airstream is initiated by pushing the tip of the tongue rapidly to the front of the oral cavity.

The air in the front of the oral cavity is forced out of the body between tightly rounded lips., by displacing the air in the front of the oral cavity.

This speech gesture is called "spitting".

b. Velaric ingressive

Speech sounds produced on the velaric ingressive airstream are called clicks.

Clicks are used in isolation as speech gestures but form part of a double articulation when used for speech sounds.

A speech sound which includes a click is accompanied by a simultaneous secondary articulation.

There are three fundamental or basic clicks:

i. Dental click

IPA symbol: [ ]

orthographic representation: ( c )

To produce a dental click, the tip of the tongue is pressed against the back of the upper teeth.

The tip of the tongue is then withdrawn abruptly from the point of articulation, causing the air pressure in the front of the oral cavity to decrease.

Exterior air enters into the front of the oral cavity, passing between mutually open lips, to compensate for the decrease in air pressure.

ii. (Post) alveolar click

IPA symbol: [ ]

orthographic representation: ( q )

To produce a (post) alveolar click, the front of the tongue is raised to press firmly against the post-alveolar region.

The front of the tongue is withdrawn abruptly from the point of articulation, causing a decrease in air pressure in the central part of the oral cavity.

Exterior air passes into the oral cavity through mutually open lips, to compensate for the decrease in air pressure.

(iii. Palato-alveolar click

IPA symbol: [ ]

To produce a palato-alveolar click, the front of the tongue is raised to press firmly against the hard palate.

The front of the tongue is withdrawn abruptly from the point of articulation, causing a decrease in air pressure in the central part of the oral cavity.

Exterior air passes into the oral cavity through mutually open lips, to compensate for the decrease in air pressure.

 

iv. Alveolar lateral click

IPA symbol: [ ]

orthographic representation: ( x )

To produce a lateral click, the blade of the tongue is pressed against the alveolar ridge causing one side of the tongue to be brought into firm contact with the corresponding side of the oral cavity.

The side of the tongue is then withdrawn abruptly from the point of articulation, causing a decrease in air pressure in the oral cavity.

Exterior air enters into the oral cavity passing between slightly spread lips to compensate for the decrease in air pressure.

 

Clicks as speech sounds

The production of a click speech sound involves two articulations and two types of airstream which are produced simultaneously.

In order for this to happen, the oral cavity is divided into two parts by raising the back of the tongue to form a point of closure with the soft palate (velar articulation).

The articulation of the click occurs in the front part of the oral cavity.

The secondary articulation occurs behind the velar articulation.

 

The production of a dental click

The back of the tongue is raised to form a point of closure with the soft palate.

The velum is raised blocking off the nasal cavity.

The tip of the tongue is then withdrawn abruptly and air flows into the oral cavity to fill the partial vacuum caused by tongue movement.

At the same time, pulmonic air is compressed in the trachea behind the velar closure.

The back of the tongue is then lowered, there is release and the air flows out of the mouth cavity between spread lips.

In the formation of the click (primary articulation) the airstream is velaric and ingressive.

In the formation of the secondary articulation, the airstream is pulmonic and egressive.

Examples taken from Xhosa / /:

/ / icici meaning ear-ring

 

The production of a (post) alveolar click

The IPA symbol is [ ]

The velum is raised, blocking off the nasal cavity.

The back of the tongue is raised to form a point of closure with the soft palate, thereby dividing the oral cavity into two sections.

The blade of the tongue is raised to touch the post-alveolar region.

The lips are mutually open.

The blade of the tongue is then withdrawn abruptly from the point of contact in the post-alveolar region, causing a decrease in air pressure in the front section of the oral cavity.

Air passes from the exterior of the body between mutually open lips into the front section of the oral cavity to compensate for the decrease in air pressure.

At the same time, pulmonic air passes through wide open or partially closed vocal folds into the back section of the oral cavity.

There is compression behind the point of closure formed by the back of the tongue and the soft palate.

The back of the tongue is then lowered from its point of contact with the soft palate causing release.

Pulmonic air flows out of the oral cavity between mutually open lips.

Note: There are two variables not specified in this description.

1. The velum may be raised or lowered, i.e. post-alveolar, palatal and dental clicks can be either nasal or oral.

2. The vocal folds will be either open - in the case of unvoiced clicks- or partially closed - in the case of voiced clicks.

Example:

/ / qala meaning begin

 

The production of a palatal click

The IPA symbol is [ ]

The velum is raised, blocking off the nasal cavity.

The back of the tongue is raised to form a point of closure with the soft palate, thereby dividing the oral cavity into two sections.

The front of the tongue is raised to touch the hard palate.

The lips are mutually open.

The front of the tongue is then withdrawn abruptly from the point of contact with the hard palate, causing a decrease in air pressure in the front section of the oral cavity.

Air passes from the exterior of the body between mutually open lips into the front section of the oral cavity to compensate for the decrease in air pressure.

At the same time, pulmonic air passes through wide open or partially closed vocal folds into the back section of the oral cavity.

There is compression behind the point of closure formed by the back of the tongue and the soft palate.

The back of the tongue is then lowered from its point of contact with the soft palate causing release.

Pulmonic air flows out of the oral cavity between mutually open lips.

Note: There are two variables not specified in this description.

1. The velum may be raised or lowered, i.e. post-alveolar, palatal and dental clicks can be either nasal or oral.

2. The vocal folds will be either open - in the case of unvoiced clicks- or partially closed - in the case of voiced clicks.

 

The production of a lateral click

The IPA symbol is: [ ]

orthographic representation: ( x )

The velum is raised, blocking off the nasal cavity.

The back of the tongue is raised to form a point of closure with the soft palate, thereby dividing the oral cavity into two sections.

The sides of the tongue are moved to form a point of closure with the sides of the oral cavity.

Lips are in a spread position.

One side of the tongue is then withdrawn abruptly from the side of the oral cavity, causing a decrease in air pressure in the front section of the mouth.

Exterior air passes through spread lips into the front section of the oral cavity to compensate for the decrease in air pressure.

At the same time, pulmonic air passes through wide open or partially closed vocal folds into the back section of the oral cavity.

There is compression.

The back of the tongue is then lowered from the point of closure with the soft palate, causing release.

Pulmonic air then passes through the oral cavitty and out of the body between spread lips.

Example:

/ / xa meaning when

 

The clicks as speech sounds

The three basic clicks are the following:

[ ] - dental

[ ] - (post) alveolar

[ ] - lateral

Each click, when used as a speech sound, has five variations.

Those variations depend on variables such as voiced or unvoiced, aspirated or unaspirated, nasal or oral.

We should note that voiced clicks, produced by pulmonic air passing through partially closed vocal folds, will not be markedly aspirated since the amount of air that can pass through partially closed vocal folds from the lungs is limited and in perceptual terms it is unaspirated.

Types of dental clicks as speech sounds:

[ ] - unvoiced unaspirated dental click

[ ] - unvoiced aspirated dental click

[ ] - voiced dental click

[ ] - voiced unaspirated nasal dental click

[ ] - voiced aspirated nasal dental click

 

Types of post-alveolar clicks as speech sounds

[ ] - unvoiced unaspirated palatal click

[ ] - unvoiced aspirated palatal click

[ ] - voiced palatal click

[ ] - voiced unaspirated nasal palatal click

[ ] - voiced aspirated nasal palatal click

 

Types of lateral clicks as speech sounds

[ ] - unvoiced unaspirated lateral click

[ ] - unvoiced aspirated lateral click

[ ] - voiced lateral click

[ ] - voiced unaspirated nasal lateral click

[ ] - voiced aspirated nasal lateral click

 

Examples from Xhosa:

/ / - cela meaning ask

/ / - chola meaning pick-up

/ / - gcoba meaning be happy

/ / - ncama meaning give up

/ / - ingca meaning grass