In Min Chinese, nasal vowels carry persistent air flow though both the mouth and the nose, producing an invariant and sustainable vowel quality. That is, this type of nasalization is synchronic and suprasegmental to the voicing. In contrast, nasal vowels in French or Portuguese are transitional, where the velum ends up constricting the mouth airway. In languages which have transitional nasal vowels, it is commonly the case that there are fewer nasal vowels than oral ones. This ap ...

See also:

Nasal vowel, Nasal vowel - Suprasegmental and transitional nasal vowels, Nasal vowel - Orthography, Nasal vowel - Example languages

Read more here: » Nasal vowel: Encyclopedia II - Nasal vowel - Suprasegmental and transitional nasal vowels