Re: Vowels?

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No line need be drawn: [R] is a vowel, just as much as [i] is.
Traditional
grammarians have it that the vowels are "a, e, i, o, u and sometimes
y",
but from an articulatory point of view, that's not the case.

(In addition to the tongue articulation difference, though, [R] as I
say
it has rounded lips.)

>>
Are you aware of the existence of rhotic vowels such as ... I don't
know the SAMPA, but it's a schwa with a r-hook on it to show r-
coloration. Those are definitely vowels, and quite close to the
approximant American r you represent with [R].

Imperative