In phonetics, a nasal release is the release of a stop consonant into a nasal. Such sounds are transcribed in the International Phonetic Alphabet with superscript nasal letters, for example as [tⁿ] in English catnip [ˈkætⁿnɪp]. In English words such as sudden in which historically the tongue made separate contacts with the alveolar ridge for the /d/ and /n/, [ˈsʌdən], many speakers today make only one contact. That is, the /d/ is released directly into the /n/: [ˈsʌdⁿn̩]. Although this is a minor phonetic detail in English (in fact, it is commonly transcribed as having no audible release: [ˈkæt̚nɪp], [ˈsʌd̚n̩]), nasal release is more important in some other languages.

Prestopped nasals

In some languages, such consonants may occur before vowels and are called prestopped nasals.

Prestopped nasals and prenasalized stops occur when the oral cavity is closed and the nasal cavity is opened by lowering the velum, but the timing of both events does not coincide. A prenasalized stop starts out with a lowered velum that raises during the occlusion, much like the [nd] in candy. A postnasalized stop or prestopped nasal begins with a raised velum that lowers during the occlusion. That causes an audible nasal release, as in English sudden.

The Slavic languages are most famous for having (non-phonemic) prestopped nasals. That can be seen in place names such as the Dniester River. The Russian word for "day", for example, is inflected день, дня, дни, дней [dʲenʲ, dnʲä, dnʲi, dnʲej], "day, day's, days, days'".

Prestopped nasals area also found in Australia. Eastern Arrernte has both prenasalized stops and prestopped nasals, but it does not have word-initial consonant clusters. Compare [mʷaɻə] "good" (with nasal stop), [ᵐbʷaɻə] "make" (with prenasalized stop), [ᵖmʷaɻə] "coolamon" (with prestopped nasal).

There is little or no phonetic difference between a "prenasalized stop" (/ⁿd/) and a cluster (/nd/). It is similar for prestopped nasals. The difference is essentially one of phonological analysis. For example, languages with word-initial /nd/ (or /ⁿd/) but no other word-initial clusters, will often be analyzed as having a unitary prenasalized stop rather than a cluster of nasal + stop. For some languages, it is claimed that a difference exists (often medially) between /ⁿd/ and /nd/. Even in such cases, however, alternative analyses are possible. Ladefoged and Maddieson^[1] investigated one such claimed case and concluded that the two sounds were better analyzed as /nd/ and /nnd/, respectively.

Final consonants with nasal release

However, some languages such as Vietnamese and Malay, which are generally described as having no audible release in final stops, actually have a short nasal release ^{[citation needed]} in such cases. Since all final stops in these two languages are voiceless, the nasal release is voiceless as well.

Although the difference is commonly chalked up to aspiration, final nasal release is contrastive in Wolof:^[2]

Contrasting releases in Wolof

Nasal release		Aspirated release
[lapᵐ̥]	'to drown'	[lapʰ]	'to be thin'
[ɡɔkᵑ̊]	'bridle rope'	[ɡɔkʰ]	'white chalk'