Implosive consonant

Implosive consonants are stops (and possibly affricates) with a mixed glottalic ingressive and pulmonic egressive airstream mechanism. That is, the airstream is controlled by moving the glottis downward in addition to expelling air from the lungs. Therefore, unlike the purely glottalic ejective consonants, implosives can be modified by phonation. Contrastive implosives are found in approximately 13% of the world's languages.

In the International Phonetic Alphabet, implosives are indicated by modifying the top of a letter (voiced stop) with a downward-facing hook: ⟨ɓ ɗ ʄ ɠ ʛ ⟩.

Articulation

During the occlusion of the stop, pulling the glottis downward rarefies the air in the vocal tract. The stop is then released. In languages where implosives are particularly salient, this may result in air rushing into the mouth, before flowing out again with the next vowel. To intake air sharply this way is to "implode" a sound.

However, probably more typically there is no movement of air at all, contrasting with the burst of the pulmonary plosives. This is the case with many of the Kru languages, for example. Note that this means implosives are phonetically sonorants (i.e. not obstruents) as the concept of sonorant is usually defined. However, phonologically implosives can pattern as both; that is, they may be phonological sonorants or obstruents depending on the language. Clements (2002) actually proposes that implosives are phonologically neither obstruents nor sonorants, and that they need to be described by the features −obstruent and −sonorant.

The vast majority of implosive consonants are voiced, meaning that the glottis is only partially closed. Because the airflow required for voicing reduces the vacuum being created in the mouth, implosives are easiest to make with a large oral cavity. Thus bilabial [ɓ] is the easiest implosive to pronounce, and also most common around the world. Velar [ɠ], on the other hand, is quite rare (and uvular [ʛ] even rarer). This is the opposite pattern to the ejective consonants, where it is the velar articulation that is most common, and the bilabial that is rare.

Types

IPA chart non-pulmonic consonants
Clicks ʘ ǀ ǃ ǂ ǁ ʘ̃ ʘ̃ˀ ʘ͡q ʘ͡qʼ ‼ Implo­sives ɓ ɗ ʄ ᶑ ɠ ʛ Eject­ives pʼ t̪ʼ tʼ ʈʼ cʼ kʼ qʼ fʼ θʼ sʼ ɬʼ ʃʼ ʂʼ ɕʼ xʼ χʼ tsʼ tɬʼ cʎ̝̥ʼ tʃʼ ʈʂʼ kxʼ kʟ̝̊ʼ qχʼ
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The attested voiced implosive stops are the following:

• voiced bilabial implosive [ɓ]
• voiced dental implosive [ɗ̪ ]
• voiced alveolar implosive [ɗ ]
• voiced retroflex implosive [ᶑ ] ("letter not explicitly IPA approved")
• voiced palatal implosive [ ʄ ]
• voiced velar implosive [ɠ ]
• voiced labial–velar implosive [ɠɓ]
• voiced uvular implosive [ʛ ]

There are no IPA symbols for implosive fricatives. Implosive fricatives are unknown, and implosive affricates unlikely. A few affricates have been reported (e.g. [ɗʒ] in Roglai and Komo; allophonic [ɗz] and [ɗɮ] in Gitxsan), but follow-up investigation may reanalyze them as something else.

Voiceless implosives

Consonants variously called "voiceless implosives", "implosives with glottal closure", or "reverse ejectives" involve a slightly different airstream mechanism, purely glottalic ingressive. Here the glottis is closed, so no pulmonic airstream is possible. The IPA once dedicated symbols ⟨ƥ ƭ ƈ ƙ ʠ ⟩ to these sounds, but these were withdrawn in 1993. They are now transcribed ⟨ɓ̥ ɗ̥ ʄ̊ ɠ̊ ʛ̥ ⟩ or occasionally ⟨pʼ↓ tʼ↓ cʼ↓ kʼ↓⟩. Some authors use a superscript left pointer, ⟨p˂ t˂ c˂ k˂⟩, but this is not an IPA symbol and has other uses.

The attested voiceless implosive stops are:

• voiceless bilabial implosive [ɓ̥]
• voiceless alveolar implosive [ɗ̥ ]
• voiceless retroflex implosive [ᶑ̥ ]
• voiceless palatal implosive [ ʄ̥ ]
• voiceless velar implosive [ɠ̊ ] (paraphonemic in English)
• voiceless uvular implosive [ʛ̥ ]
• voiceless labial–velar implosive [ɠ̊ɓ̥] (in Igbo per Floyd 1981)

Other implosives

Nasals have been reported to have implosive releases; however, phonologically these are sequences such as /N-ɓ/ and phonetically they may be weakened implosive stops rather than implosive nasals.

Attested implosive consonants
(excluding secondary phonations and articulations)

	Bilabial	Linguo­labial	Dental	Alveolar	Labial– alveolar	Retroflex	Palatal	Velar	Labial– velar	Uvular
Stop	ɓ ƥ		ɗ̪ ƭ̪	ɗ ƭ		ᶑ ƭ̢	ʄ ƈ	ɠ ƙ	ɠ͡ɓ ƙ͜ƥ	ʛ ʠ
Affricate	(theoretical)
Nasal	? m̩ɓ			? n̩ɗ

Occurrence

Implosives are widespread among the languages of Sub-Saharan African and Southeast Asia and are found in a few languages of the Amazon Basin. They are rarely reported elsewhere but occur in scattered languages such as the Mayan languages in North America, Saraiki and Sindhi in the Indian subcontinent, as well as Vietnamese. They appear to be entirely absent from northern Eurasia and Australia, even from the Australian ceremonial language Damin, which uses every other possible airstream mechanism.

However, fully voiced stops are often slightly implosive, although it is not always described explicitly if there is no contrast with modal-voiced plosives, as occurs around the world, from Maidu to Thai to many Bantu languages, including Swahili.

Sindhi and Saraiki have an unusually large number of contrastive implosives, with /ɓ ᶑ ʄ ɠ/. Although Sindhi has a dental–retroflex distinction in its plosives, with /b d ɖ ɟ ɡ/, this contrast is neutralized in the implosives. A contrastive retroflex implosive /ᶑ / may however occur in Ngad'a, a language spoken in Flores, Indonesia.

More examples can be found in the articles on individual implosives.

Voiceless implosives are quite rare but are found in languages as varied as the Owere dialect of Igbo in Nigeria (/ƥ/ /ƭ/), Krongo in Sudan, the Uzere dialect of Isoko, the closely related Lendu and Ngiti languages in the Democratic Republic of Congo, Serer in Senegal (/ƥ ƭ ƈ/), and some dialects of the Poqomchi’ and Quiche languages in Guatemala (/ƥ ƭ/). Owere Igbo has a seven-way contrast among bilabial stops, /pʰ p ƥ bʱ b ɓ m/, and its alveolar stops are similar. It does not appear that the dorsal stops [ƙ] [ʠ] are attested in the literature as speech sounds, but /ʠ/ has been claimed for Kaqchikel. Lendu has been claimed to have voiceless /ɓ̥ ɗ̥ ɠ̊/, but these may actually be creaky-voiced implosives.

Some English speakers use a voiceless velar implosive [ƙ] to imitate the "glug-glug" sound of liquid being poured from a bottle, but others use a voiced implosive [ɠ].

Bibliography

• Demolin, Didier; Ngonga-Ke-Mbembe, Hubert; & Soquet, Alain. (2002). Phonetic characteristics of an unexploded palatal implosive in Hendo. Journal of the International Phonetic Association, 32, 1-15.
• Maddieson, Ian. (1984). Patterns of sounds. Cambridge studies in speech science and communication. Cambridge: Cambridge University Press.