Stop consonant
A
stop,
plosive, or
occlusive is a
consonant sound produced by stopping the airflow in the
vocal tract. The term
plosive is reserved for
oral (non-nasal) stops: that is, stops with a release burst.
All languages in the world have stops and most have at least [p], [t], [k], [n], and [m]. Colloquial
Samoan lacks the dentals [t] and [n], and the northern
Iroquoian languages lack the labials [p] and [m]. Several of the
Chimakuan,
Salishan, and
Wakashan languages around
Puget Sound lack
nasal stops.
In the articulation of the stop, three phases can be distinguished:
*
Catch: The airway closes so that no air can escape through the mouth (hence the names
stop). With nasal stops, the air escapes through the nose.
*
Hold or
occlusion: The airway stays closed, causing a pressure difference to build up (hence the name
occlusive).
*
Release or
burst: The closure is opened. In the case of plosives, the released airflow produces a sudden impulse causing an audible sound (hence the name
plosive).
In many languages, such as
Malay and
Vietnamese, final stops lack a release burst, or have a
nasal release. See
Unreleased stop.
In
affricate stops, the release is a
fricative.
Nasal stops are differentiated from
oral stops only by a lowered
velum that allows the air to escape through the nose during the occlusion.
Nasal stops are acoustically
sonorants, as they have a non-turbulent airflow and are nearly always voiced, but they are articulatorily
obstruents, as there is complete blockage of the oral cavity.
A
prenasalized stop starts out with a lowered velum that raises during the occlusion. The closest examples in English are consonant clusters such as the [nd] in
candy, but many languages have prenasalized stops that behave as single consonants.
Swahili is well known for having words that begin with sounds like [mp] or [nd].
A
postnasalized stop begins with a raised velum that lowers during the occlusion. This causes an audible nasal
release, as in English
sudden.
Russian and other Slavic languages have words that begin with [dn], which can be seen in the name of the
Dnieper River.
Note that the terms
prenasalization and
postnasalization are normally only used in languages where these sounds are phonemic, that is, not analyzed into sequences of plosive plus nasal stop.
Voiced stops are articulated with simultaneous vibration of the
vocal cords,
voiceless stops without. Plosives are commonly voiceless, whereas nasal stops are only rarely so.
In
aspirated stops, the voice onset (the time when the
vocal cords begin to vibrate) comes perceivably later than the release of the stop. The duration between the release of the stop and the voice onset is called
voice onset time (VOT).
Tenuis stops have a voice onset time close to zero, meaning that voicing begins when the stop is released. Voiced stops have a negative voice onset time, meaning the voicing begins before the stop is released. A stop is called "fully voiced" if it is voiced during the entire occlusion. In English, however, initial voiced plosives like [b] or [d] are only partially voiced, meaning that voicing picks up sometime during the occlusion. Aspirated stops have a voice onset time greater than zero, so that there is a period of voiceless airflow (a phonetic
) before the onset of the vowel.
In most dialects of English, the final
g in the word
bag is likely to be fully voiced, while the initial
b will be only partially voiced. Initial voiceless plosives, like the
p in
pie, are aspirated, with a palpable puff of air upon release, while a plosive after an
s, as in
spy, is tenuous. If you speak near a candle flame, you will see that the flame will flicker more when you say
pie, tie, chi than when you say
spy, sty, sky.
Length
In a
geminate or
long stop, the occlusion lasts longer than in normal stops. In languages where stops are only distinguished by length (e.g. Arabic, Ilwana, Icelandic), the long stops may last up to three times as long as the
short stops.
Italian is well known for its geminate stop, as the double
t in the name
Vittoria takes just as long to say as the
ct does in English
Victoria.
Note that there are many languages where the features voice, aspiration, and length reinforce each other, and in such cases it may be hard to tell which of these features predominates. In such cases the terms
fortis is sometimed used for aspiration or gemination, while
lenis is used for single, tenuous or voiced stops. Beware, however, that the terms
fortis and
lenis are poorly defined, and their meanings vary from source to source.
Stops may be made with more than one airstream mechanism. The normal mechanism is
pulmonic egressive, that is, with air flowing outward from the lungs. All languages have pulmonic stops. Some languages have stops made with other mechanisms as well:
ejective stops (
glottalic egressive),
implosive stops (
glottalic ingressive), or
click consonants (
velaric ingressive).
A
fortis stop (in the narrow sense) is produced with more muscular tension than a
lenis stop (in the narrow sense). However, this is difficult to measure, and there is usually debate over the actual mechanism of alleged fortis or lenis consonants.
There are a series of stops in
Korean, sometimes written with the IPA symbol for ejectives, which are produced using "
stiff voice", meaning there is increased contraction of the glottis than for normal production of voiceless stops. The indirect evidence for stiff voice is in the following vowels, which have a higher fundamental frequency than those following other stops. The higher frequency is explained as a result of the glottis being tense. Other such
phonation types include
breathy voice, or murmur;
slack voice; and
creaky voice.
Here are the oral stops (plosives) granted dedicated symbols in the
IPA. See also the
nasal stops.
*
voiceless bilabial plosive*
voiced bilabial plosive*
voiceless alveolar plosive*
voiced alveolar plosive*
voiceless retroflex plosive*
voiced retroflex plosive*
voiceless palatal plosive*
voiced palatal plosive*
voiceless velar plosive*
voiced velar plosive*
voiceless uvular plosive*
voiced uvular plosive*
epiglottal plosive*
glottal stop, , (aspirated word-initially, tenuis in clusters with
s)
, , (in most dialects: partially voiced word-initially, fully voiced intervocalically)
, , (fully voiced nasal stops)
(glottal stop, not as a
phoneme in most dialects)
*
Continuant, the antonym of a stop
*
List of phonetics topics
