Nasalization

Many languages have nasal vowels to different degrees, but only a minority of world languages around the world have nasal vowels as contrasting phonemes. That is the case, among others, of French, Portuguese, Hindustani, Nepali, Breton, Gheg Albanian, Hmong, Hokkien, Yoruba, and Cherokee. Those nasal vowels contrast with their corresponding oral vowels. Nasality is usually seen as a binary feature, although surface variation in different degrees of nasality caused by neighboring nasal consonants has been observed.^[2]

There are languages, such as in Palantla Chinantec, where vowels seem to exhibit three contrastive degrees of nasality: oral e.g. [e] vs lightly nasalized [ẽ] vs heavily nasalized [e͌],^[3][4] although Ladefoged and Maddieson believe that the lightly nasalized vowels are best described as oro-nasal diphthongs.^[5] Note that Ladefoged and Maddieson's transcription of heavy nasalization with a double tilde might be confused with the extIPA adoption of that diacritic for velopharyngeal frication.

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^{[citation needed]}.

Nasalized versions of other consonant sounds also exist but are much rarer than either nasal occlusives or nasal vowels. The Middle Chinese consonant 日 ([ȵʑ]; [ʐ] in modern Standard Chinese) 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]/[n̠ʲ] 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.^{[further explanation needed]} In Old and Middle Irish, the lenited ⟨m⟩ was a nasalized bilabial fricative [β̃].^[6]

Ganza^[7] has a phonemic nasalized glottal stop [ʔ̃] while Sundanese has it allophonically; nasalized stops can occur only with pharyngeal articulation or lower, or they would be simple nasals.^[8] 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; voiced retroflex nasal flaps are common intervocalic allophones of /ɳ/ in South Asian languages.

A nasal trill [r̃] has been described from some dialects of Romanian, and is posited as an intermediate historical step in rhotacism. However, the phonetic variation of the sound is considerable, and it is not clear how frequently it is actually trilled.^[9] Some languages contrast /r, r̃/ like Toro-tegu Dogon^[10] and Inor. A nasal lateral has been reported for some languages, Nzema language contrasts /l, l̃/.^[11]

Other languages, such as the Khoisan languages of Khoekhoe and Gǀui, as well as several of the !Kung languages, include nasal click consonants. Nasal clicks are typically with a nasal or superscript nasal preceding the consonant (for example, velar-dental ⟨ŋ͡ǀ⟩ or ⟨ᵑǀ⟩ and uvular-dental ⟨ɴ͡ǀ⟩ or ⟨ᶰǀ⟩).^[12] Nasalized laterals such as [‖̃] (a nasalized lateral alveolar click) are easy to produce but rare or nonexistent as phonemes; nasalized lateral clicks are common in Southern African languages such as Zulu. Often when /l/ is nasalized, it becomes [n].

Besides nasalized oral fricatives, there are true nasal fricatives, or anterior nasal fricatives, previously called nareal fricatives. They are sometimes produced by people with disordered speech. The turbulence in the airflow characteristic of fricatives is produced not in the mouth but at the anterior nasal port, the narrowest part of the nasal cavity. (Turbulence can also be produced at the posterior nasal port, or velopharyngeal port, when that port is narrowed – see velopharyngeal fricative. With anterior nasal fricatives, the velopharyngeal port is open.) A superimposed homothetic sign that resembles a colon divided by a tilde 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.

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.

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.^[13] That happened in French, most of whose final consonants disappeared, but its final nasals made the preceding vowels become nasal, which introduced a new distinction into the language. An example is vin blanc [vɛ̃ blɑ̃] 'white wine', ultimately from Latin vinum and blancum.

• Eclipsis, a similar process in Gaelic that is often called "nasalization"
• Nasal consonant
• Nasal release
• Nasal vowel
• Nasality
• Prenasalized consonant

• Ladefoged, Peter; Maddieson, Ian (1996). The Sounds of the World's Languages. Oxford: Blackwell. ISBN 0-631-19815-6.