The term 'glottal stop' is perhaps the only one from
phonetics that has entered common use. It is a normal sound in many languages, though has not yet become one in standard English. I shall first give examples from other language groups, then discuss the phonetic
articulation in more detail. The
SAMPA symbol for this sound is
[?].
Semitic
It is common in the
Semitic languages. It is the original value of the
Hebrew aleph and the
Arabic letter
alif, the first of their alphabets. Since the glottal stop did not occur in Ancient Greek this letter was adopted as
alpha for the vowel
A.
I don't know enough about Modern Hebrew to comment, so the following is solely about the Biblical language; and the Arabic is Quranic.
It can occur initially and medially in Hebrew words. In some words aleph was not pronounced: לא lo 'not', ראש rosh 'head'. In these cases it is after a vowel but not followed by another.
In Arabic it can occur in any position, as in رأس ra?s 'head'. In the other corresponding word it has become silent: لا laa 'no'. The letter alif no longer represents the glottal stop, but has become a bearer of vowel signs and the marker of the long vowel aa. When the glottal stop is actually pronounced it is marked by an additional hook-shaped symbol ء hamza, usually on top of the alif as أ but occasionally elsewhere, depending on the phonetic context. The name hamza is sometimes used generally in linguistics for a glottal stop.
In the Semitic languages, words could not begin with a vowel. Any word that we transcribe with one actually begins with either the glottal stop or another sound ayin/ain, a pharyngeal fricative.
However, in Maltese, a descendant of Arabic, the original glottal stop has been lost entirely, but the Arabic sound q has changed into it, and the Maltese letter Q represents a glottal stop.
Austronesian
The
Austronesian family covers
Philippine,
Indonesian, and
Polynesian languages. In Philippine languages such as
Tagalog, typically the glottal stop is used as a separator between vowels such as
aa or
oo, instead of treating them as long vowels.
In Indonesian, a word can't begin with a vowel. It can end with a vowel, but can't end with k. In the word kanak 'small child' the final k is a glottal stop. In the word anak 'child', there is an unwritten glottal stop in front of the first vowel. It does not really occur between vowels, though it may be heard in the odd word like maaf 'excuse me'.
In many Polynesian languages an original consonant k has changed into a glottal stop. For example, the legendary homeland of the Maoris is called Hawaiki, corresponding to the Hawaiian name Hawai'i and to the main Samoan island, Savai'i. (In Hawaiian a new k sound has arisen from earlier t: for example Maori tiki is Hawaiian ki'i.) The Hawaiian name for the vertical stroke symbolizing it is 'okina. The sound occurs between vowels and initially. No consonant can occur at the end of a syllable in Polynesian. In Samoan the consonant is described as "weak", a bare hiatus between vowels, and serving to shorten a vowel initially.
Germanic
The
sociological situation with English glottal stop has been discussed in previous write-ups. Phonetically, there is not just one simple replacement going on. This is one of the gradual changes I discuss in
Changes in Southern British pronunciation: for most people, even fairly conservative speakers, they probably use glottal stops before another
consonant, as in
not really, in casual speech. Different speech
registers have different phonetics even in the one person. The marked feature of the London
Cockney accent and the more widespread modern accent called
Estuary English is that these stops are used in a wider range of positions, the process known as
glottalling.
Even in more conservative Received Pronunciation, where the t is not replaced entirely, a phenomenon called preglottalization can occur. I am not clear about this and don't know how much it occurs in my own speech; I would have to read more about it and test myself. But briefly, some stops can be preceded by a weak glottal stop in some positions: in ma'ttress but not in hopeless.
It is sometimes heard between words to prevent a linking R: as in India Office said as India'Office rather than IndiarOffice.
The glottal stop can occur initially in English in emphatic expressions like uh-oh and absolutely awful!, but normally it does not.
In German and Dutch however, words never begin with a vowel, except when closely connected with a preceding word. Normally a word written with initial vowel has a preceding glottal stop, as eins 'one' = [?aIns]. It remains when a prefix is added, as in geantwortet 'answered' from antworten.
In Danish there is the stød, not a distinctive glottal stop phoneme in its own right, but a simultaneous glottal break that can occur on both consonants and vowels.
Phonetics
In some respects it is a
stop like any other: a brief
closure of the mouth or throat, with abrupt
release. But since the closure is made in the
glottis (or
larynx), the source of many features of speech, such as
voice, it is unusual. It cannot be
voiced, for example. While a
bilabial stop
[p] is blocked at the lips, it can simultaneously admit continued
vibration through the
glottis, giving the voiced counterpart
[b]. This
coarticulation between the bilabial and
glottal positions is not possible for the glottal stop itself.
The preglottalization of RP English and the stød of Danish are examples of coarticulation of a glottal stoppage with some other sound. In some of the tonal languages of South-East Asia, such as Burmese and Vietnamese, one of the tones is "creaky", that is has a catch in it. When the vocal chords in the glottis are vibrated so as to give the effect of repeated constrictions through a sound, this is called creaky voice, though this is a kind of continuing voice, not a complete stop.
The most common way a glottal stop is coarticulated with another sound is in the class of stops called ejectives, occurring in Georgian, Amharic, Quechua, and many other languages. In these there are not just two places of stoppage, one of which is the glottis, but the glottis is moved upward to compress the trapped air, so that the release has a more forceful pop.
This, I believe, is the reason why we say a few languages, such as Arabic, German, and Indonesian, obligatorily have glottal stops before their initial vowels, whereas most languages don't. In one sense, the opening of the vocal chords when you begin to speak is a kind of release of a glottal stoppage. The reason we don't hear it as a glottal stop in English is that it's a normal plosive release, of no great strength, whereas the hamza-initial languages like German and Arabic have a glottal ejective in this position.
This might also explain the nature of the weak Samoan stop, as in fa'a-Samoa 'in the Samoan manner', described as a mere hiatus. It might be that this is a glottal plosive, whereas in London English [fla?a] 'flutter' or Arabic [bada?a] 'he began' it's a glottal ejective. But this bit is my own speculation.