Prenasalized consonant

Prenasalized consonants are phonetic sequences of a nasal and an obstruent (or occasionally a non-nasal sonorant) that behave phonologically like single consonants. When unambiguous, prenasalized consonants may simply be transcribed e.g. ⟨mb⟩. In the IPA, a tie bar may be used to specify that these are single segments, as in ⟨m͡b⟩ or ⟨m͜b⟩. The tie bar is commonly omitted. Another common transcription practice is to make the nasal superscript: ⟨ᵐb⟩, especially when it is phonetically distinct from a nasal-stop sequence. An old convention of the IPA was to mark the nasal as 'short' until the short and the nonsyllabic signs diverged, as in ⟨m̆b⟩.

The primary reason for considering these to be single consonants, rather than clusters as in English finger or member, lies in their behavior; however, there may also be phonetic correlates which distinguish prenasalized consonants from clusters. Because of the additional difficulty in both articulation and timing, prenasalized fricatives and sonorants are not as common as prenasalized stops or affricates, and the presence of the former implies the latter. Only three languages (Sinhala, Fula, Selayarese) have been reported to have a contrast between prenasalized consonants (N͜C) and their corresponding clusters (NC).

In most languages, when a prenasalized consonant is described as "voiceless", it is only the oral portion that is voiceless, and the nasal portion is modally voiced. Thus, a language may have "voiced" [mb nd ɳɖ ɲɟ ŋɡ ɴɢ] and "voiceless" [mp nt ɳʈ ɲc ŋk ɴq]. However, in some Southern Min (including Taiwanese) dialects, voiced consonants are preceded by voiceless prenasalization: [m̥b n̥d n̥ɺ ŋ̊ɡ]. Yeyi has prenasalized ejectives and clicks like /ntsʼ, ŋkʼ, ŋᵏ!ʰ, ŋᶢ!/. Nizaa has prenasalized implosives like /mɓ, nɗ/. Adzera has a /nʔ/.

Prenasalized stops may be distinguished from post-oralized or post-stopped nasals (orally released nasals), such as the [mᵇ nᵈ ɲᶡ ŋᶢ] of Acehnese and similar sounds (including voiceless [mᵖ]) in many dialects of Chinese. (At least in the Chinese case, nasalization, in some dialects, continues in a reduced degree to the vowel, indicating that the consonant is partially denasalized, rather than actually having an oral release.) No language is believed to contrast the two types of consonant, which are distinguished primarily by a difference in timing (a brief nasal followed by longer stop, as opposed to a longer nasal followed by brief stop).