If a language has to maintain a high number of vowel distinctions which are perceptually close to each other, then the addition of distinctive vowel nasalization creates an unstable system … leading to elimination of distinctively nasal vowels or reducing the number of oral vowels (which is rare).
Standardized
IF there is a high number of vowel distinctions which are perceptually close to each other, THEN the addition of distinctive vowel nasalization creates an unstable system leading to elimination of distinctively nasal vowels or reducing the number of oral vowels (which is rare).
Keywords
nasal, vowel, nasalization
Domain
phonology
Type
no genuine implication; rather: provided that
Status
diachronic
Quality
statistical
Basis
American English, Swedish (both Germanic), Hindi (Indo-Iranian), French, Brazilian Portuguese (both Romance, all IE), Amoy Chinese (Sinitic, Sino-Tibetan)
This diachronic implication is speculative and is not based directly on the given sample of languages.