Re: the sound [a]

Barbara Blithers;
IIRC from my Catford book on learning phonetics that no language uses "pure"
cardinal vowels; they're *all* a bit off, some more so than others.  Thus
even [phonetic] transcriptions of all languages /phonemized/ to the nearest
cardinal and avoided messy diacritics unless comparing vowel quality between
different languages/dialects.

The passage was a warning that just because one was used to, say [a], in the
transcription of one language it'd be an error to use that sound when trying
to reproduce the [a] in another language's transcription because it wouldn't
be exactly the same vowel.

If that is true then it might be possible that all languages have an /a/
vowel (ie a vowel close to [a]), but not the cardinal [a].

Barbara