 | This article has multiple issues. Please helpimprove it or discuss these issues on thetalk page.(Learn how and when to remove these messages) (Learn how and when to remove this message)
|
Inphonetics, theairstream mechanism is the method by which airflow is created in thevocal tract. Along withphonation andarticulation, it is one of three main components of speech production. The airstream mechanism is mandatory for most sound production and constitutes the first part of this process, which is calledinitiation.
The organ generating the airstream is called theinitiator and there are three initiators used phonemically in non-disordered human oral languages:
There are also methods of making sounds that do not require the glottis. These mechanisms are collectively calledalaryngeal speech mechanisms (none of these speech mechanisms are used in non-disordered speech):
Percussive consonants are produced without any airstream mechanism.[4]
[4] Any of the three principal initiators − diaphragm, glottis or tongue − may act by either increasing or decreasing the pressure generating the airstream. These changes in pressure often correspond to outward and inward airflow, and are therefore termedegressive andingressive respectively.
Of these six resulting airstream mechanisms, four are found lexically around the world, alongside the percussive sounds produced without an airstream mechanism, for a total of five:
That leavespulmonic ingressive andlingual (velaric) egressive as the only two airstream mechanisms produced by the three main initiators that are not found lexically in the world.
These mechanisms may be combined into airstreamcontours, such as clicks which release into ejectives.
In normal vocabulary, the variousKhoisan languages have pulmonic, ejective, and click consonants; theChadic languages, someMayan languages, and scattered Nilo-Saharan languages such asGumuz,Uduk andMeʼen have pulmonic, implosive, and ejective consonants, and theNguni languages of the Bantu family utilize all four, – pulmonic, click, implosive, and ejective, – as does theDahalo language of Kenya. Most other languages utilize at most two airstream mechanisms.
Ininterjections, the other two mechanisms may be employed. For example, in countries as diverse as Sweden, Turkey, and Togo, a pulmonic ingressive ("gasped" or "inhaled") vowel is used forback-channeling or to express agreement, and in France a lingual egressive (a "spurt") is used to express dismissal. The only language where such sounds are known to be contrastive in normal vocabulary is the extinct ritual languageDamin (also the only language outside Africa with clicks); however, Damin appears to have been intentionally designed to differ from normal speech.
Initiation by means of thelungs (actually the diaphragm and ribs) is calledpulmonic initiation. The vast majority of sounds used in human languages arepulmonic egressives. In most languages, including all the languages of Europe (excluding theCaucasus), allphonemes are pulmonic egressives.
The only attested use of a phonemic pulmonic ingressive is a lateral fricative inDamin, a ritual language formerly used by speakers ofLardil inAustralia. This can be written with the extended version of theInternational Phonetic Alphabet as[ɬ↓ʔ].!Xóõ has ingression as a phonetic detail in one series of its clicks, which areingressive voiceless nasals with delayed aspiration,[↓ŋ̊ʘʰ↓ŋ̊ǀʰ↓ŋ̊ǁʰ↓ŋ̊!ʰ↓ŋ̊ǂʰ].Peter Ladefoged considers these to be among the most difficult sounds in the world. Other languages, for example inTaiwan, have been claimed to have pulmonic ingressives, but these claims have either proven to be spurious or to be occasional phonetic detail.
Ininterjections, but not in normal words, pulmonic ingressive vowels or words occur on all continents.[6] This is commonly done forback-channeling (as with[ə↓] inEwe) or affirmation (as with[ɸʷ↓] inSwedish). In English, an audible intake of breath,[hːː↓], or an indrawn consonant such as[tʰ↓] or[p͡t↓] is used in a conversation to indicate that someone is about to speak or is preparing to continue speaking.[7] In some languages, such asFinnish andAmharic, entire phrases may be uttered with an ingressive airstream. (Seeingressive sound.)
It is possible to initiate airflow in the upper vocal tract by means of the vocal cords orglottis. This is known asglottalic initiation.
For egressive glottalic initiation, one lowers the glottis (as if to sing a low note), closes it as for aglottal stop, and then raises it, building up pressure in the oral cavity and uppertrachea. Glottalic egressives are calledejectives. The glottis must be fully closed to form glottalic egressives, or the air column would flow backwards over it; it is therefore impossible to pronouncevoiced ejectives. Ejective allophones of voiceless stops occur in many varieties of English at the ends ofintonation units.[8]
For ingressive glottalic initiation, the sequence of actions performed in glottalic pressure initiation is reversed: one raises the glottis (as if to sing a high note), closes it, and then lowers it to create suction in the upper trachea and oral cavity. Glottalic ingressives are calledimplosives, although they may involve zero airflow rather than actual inflow. Because the air column would flow forwards over the descending glottis, it is not necessary to fully close it, and implosives may be voiced; indeed, voiceless implosives are exceedingly rare.
It is usual for implosives to be voiced. Instead of keeping the glottis tightly closed, it is tensed but left slightly open to allow a thin stream of air through. Unlike pulmonic voiced sounds, in which a stream of air passes through a usually-fixed glottis, in voiced implosives a mobile glottis passes over a nearly motionless air column to cause vibration of the vocal cords.Phonations that are more open than modal voice, such as breathy voice, are not conducive to glottalic sounds because in these the glottis is held relatively open, allowing air to readily flow through and preventing a significant pressure difference from building up behind the articulator.
Because the oral cavity is so much smaller than the lungs,vowels andapproximants cannot be pronounced with glottalic initiation. So-calledglottalized vowels and other sonorants use the more common pulmonic egressive airstream mechanism.
There is no clear divide between pulmonic and glottalic sounds. Some languages may have consonants which are intermediate. For example, glottalized consonants in London English, such as thet inrat[ˈɹæʔt], may be weakly ejective. Similarly, fully voiced stops in languages such asThai,Zulu, andMaidu are weakly implosive. This ambiguity does not occur with the next airstream mechanism, lingual, which is clearly distinct from pulmonic sounds.[9]
 | This sectionneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources in this section. Unsourced material may be challenged and removed.(July 2020) (Learn how and when to remove this message) |
The third form of initiation in human language islingual orvelaric initiation, where a sound is produced by a closure at two places of articulation, and the airstream is formed by movement of the body of the tongue. Lingual stops are more commonly known asclicks, and are almost universally ingressive. The wordlingual is derived from Latinlingua, which means tongue.
To produce alingual ingressive airstream, first close the vocal tract at two places: at the back of the tongue, as in avelar oruvular stop, and simultaneously with the front of the tongue or the lips, as in acoronal orbilabial stop. These holds may be voiceless, voiced, or nasalized. Then lower the body of the tongue to rarefy the air above it. The closure at the front of the tongue is opened first, as the click "release"; then the closure at the back is released for the pulmonic or glottalic click "accompaniment" or "efflux". This may beaspirated,affricated, or evenejective. Even when not ejective, it is not uncommon for the glottis to be closed as well, for a triply articulated consonant, and this third closure is released last to produce a glottalized click. Clicks are found in very few languages, notably theKhoisan languages of southern Africa and some nearby tongues such asZulu. They are more often found in extra-linguistic contexts, such as the "tsk tsk" sound many Westerners use to express regret or pity (adental click), or the clucking noise used by manyequestrians to urge on their horses (alateral click).
Lingual egressive initiation is performed by reversing the sequence of a lingual ingressive: the front and back of the tongue (or lips and back of the tongue) seal off the vocal cavity, and the cheeks and middle of the tongue move inward and upward to increase oral pressure. The only attested use of a lingual egressive is a bilabial egressive "spurt" inDamin. Transcribing this also requires the use of the Extended IPA,[ʘ↑].
Since the air pocket used to initiate lingual consonants is so small, it is not thought to be possible to produce lingualfricatives,[citation needed] vowels, or other sounds which require continuous airflow.
Clicks may bevoiced, but they are more easilynasalized. This may be because the vocal cavity behind the rearmost closure, behind which the air passing through the glottis for voicing must be contained, is so small that clicks cannot be voiced for long. Allowing the airstream to pass through the nose enables a longer production.
Nasal clicks involve a combination of lingual and pulmonic mechanisms. The velum is lowered so as to direct pulmonic airflow through the nasal cavity during the lingual initiation. This nasal airflow may itself be egressive or ingressive, independently of the lingual initiation of the click. Nasal clicks may be voiced, but are very commonly unvoiced and even aspirated, which is rare for purely pulmonic nasals.
| This sectionneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources in this section. Unsourced material may be challenged and removed.(July 2020) (Learn how and when to remove this message) |
In some treatments, complex clicks are posited to have airstreamcontours, in which the airstream changes between the front (click) and rear (non-click) release. There are two attested types:Linguo-pulmonic consonants, where the rear release is a uvular obstruent such as[q] or[χ]; andlinguo-glottalic consonants, where the rear release is an ejective such as[qʼ] or[qχʼ].
Not only are simultaneous (rather than contour) implosive clicks possible, i.e. velar (e.g.[ɠ͡ǀ]), uvular ([ʛ͡ǀ]), andde facto front-closed palatal ([ʄ͡ǀ]), but velar implosive clicks are easier to produce than modally voiced clicks. However, they are not attested in any language.[10]
| This sectionneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources in this section. Unsourced material may be challenged and removed.(July 2020) (Learn how and when to remove this message) |
Consonants may be pronounced without any airstream mechanism. These arepercussive consonants, where the sound is generated by one organ striking another. Percussive consonants are not phonemic in any known language, though theextensions to the IPA for disordered speech provide symbols for abilabial percussive[ʬ] (smacking lips) and abidental percussive[ʭ] (gnashing teeth). The only percussive known to be used in nondisordered speech is asublingual percussive[¡] (a tongue slap) that appears allophonically in the release ofalveolar clicks in theSandawe language of Tanzania.[11]
| Bilabial | Bidental | Sublingual |
|---|---|---|
| ʬⓘ | ʭⓘ | ¡ⓘ |
