nasais

Nasais, or nasal sounds, are a class of consonants produced with the velum lowered, allowing air to escape through the nasal cavity. During articulation, the oral tract is closed or narrowed, while the nasal port remains open, creating resonance in the nasal cavity and giving these sounds their characteristic nasal quality. Nasais are typically voiced, though voiceless variants can occur as allophones in some languages.

The most common nasais are bilabial [m], alveolar [n], and velar [ŋ], as in words such as "mat," "nap," and "sing." Other articulations exist across languages, including dental, palatal, or retroflex nasals. In phonology, nasais are considered sonorants and can contrast with oral stops, fricatives, and approximants in many systems. They can appear as separate phonemes or as part of a broader nasal system with harmony processes that spread nasality to adjacent vowels and consonants.

Nasais often participate in nasalization of surrounding vowels; the presence of a nasal consonant or nasal vowel can cause adjacent vowels to adopt a nasal quality. Some languages have nasal vowels as distinct phonemic elements, where the vowel itself carries nasal resonance regardless of subsequent consonants. Across the world's languages, nasais play a major role in syllable structure and phonotactics; they commonly occur at the start, middle, or end of syllables and can sometimes function as syllable nuclei in languages with limited vowel inventories.

See also: nasal consonant, nasalization, nasal vowel.