Nasalization

Nasal vowels

Nasal vowels are found in various languages around the world, such as French, Portuguese, Breton, Hindi, Hmong, Hokkien, Yoruba and Cherokee. Those nasal vowels contrast with oral vowels. Many languages, however, have only oral vowels or do not contrast oral and nasal vowels.

There are occasional cases for vowels showing contrasting degrees of nasality.. One such is Palantla Chinantec.

Nasal consonants

By far the most common nasal sounds are nasal consonants such as [m], [n] or [ŋ]. Most nasal consonants are occlusives, and airflow through the mouth is blocked and redirected through the nose. Their oral counterparts are the stops.

Nasalized consonants

Nasalized versions of other consonant sounds also exist but are much rarer than either nasal occlusives or nasal vowels. Some South Arabian languages use phonemic nasalized fricatives, such as /z̃/, which sounds something like a simultaneous [n] and [z]. The Chinese consonant 日 ([ȵʑ]) has an odd history; for example, it has evolved into [ʐ] and [ɑɻ] (or [ɻ] and [ɚ] respectively, depending on accents) in Standard Chinese; [z]/[ʑ] and [n] in Hokkien; [z]/[ʑ] and [n]/[ɲ] while borrowed into Japan. It seems likely that it was once a nasalized fricative, perhaps a palatal [ʝ̃].

In Coatzospan Mixtec, fricatives and affricates are nasalized before nasal vowels even when they are voiceless. In the Hupa, the velar nasal /ŋ/ often has the tongue not make full contact, resulting in a nasalized approximant, [ɰ̃]. That is cognate with a nasalized palatal approximant [ȷ̃] in other Athabaskan languages.

In Umbundu, phonemic /ṽ/ contrasts with the (allophonically) nasalized approximant [w̃] and so is likely to be a true fricative rather than an approximant. In Old and Middle Irish, the lenited ⟨m⟩ was a nasalized bilabial fricative.

Sundanese has an allophonic nasalized glottal stop [ʔ̃]; nasalized stops can occur only with pharyngeal articulation or lower, or they would be simple nasals. Nasal flaps are common allophonically. Many West African languages have a nasal flap [ɾ̃] (or [n̆]) as an allophone of /ɾ/ before a nasal vowel; Pashto, however, has a phonemic nasal retroflex lateral flap.

Other languages, such as the Khoisan languages of Khoekhoe and Gǀui, as well as several of the !Kung languages, include nasal click consonants. Nasalization of the phonemes is denoted with a superscript ⟨ᵑ⟩ preceding the consonant (for example, ⟨ᵑǂ⟩). Nasalized laterals such as [l̃] are easy to produce but rare or nonexistent as phonemes; often when [l] is nasalized, it becomes [n].

True nasal (nareal) fricatives

Besides nasalized oral fricatives, there are true nasal fricatives, previously called nareal fricatives, that are sometimes produced by people with disordered speech. The turbulence in the airflow characteristic of fricatives is produced not in the mouth but in the nasal cavity. A tilde and trema diacritic (two dots representing the nostrils) is used for this in the extensions to the IPA: [n͋] is a voiced alveolar nasal fricative, with no airflow out of the mouth, and [n̥͋] is the voiceless equivalent; [v͋] is an oral fricative with simultaneous nasal frication. No known language makes use of nasal fricatives in non-disordered speech.

Denasalization

Nasalization may be lost over time. There are also denasal sounds, which sound like nasals spoken with a head cold. They may be found in non-pathological speech as a language loses nasal consonants, as in Korean.

Contextual nasalization

Vowels assimilate to surrounding nasal consonants in many languages, such as Thai, creating nasal vowel allophones. Some languages exhibit a nasalization of segments adjacent to phonemic or allophonic nasal vowels, such as Apurinã.

Contextual nasalization can lead to the addition of nasal vowel phonemes to a language. That happened in French, where most final consonants disappeared, but in the case of final nasals, the preceding vowels became nasal and introduced a new distinction into the language. An example is vin blanc [vɛ̃ blɑ̃] ('white wine'), ultimately from Latin vinum and blancum.