An Introduction to French Pronunciation

92 Vowel Length
12.8 Is Vowel Length Ever Phonemic in French?
12.8.1 If the indications given above are followed consistently,
the results in respect of vowel length will always
be acceptable. There are, however, certain words in which
an alternative pronunciation is possible. More specifically,
certain words that, according to rule 5 (12.7), would have
a short vowel may also be pronounced with a long vowel, e.g.
maître /mεtr/ or /mε:tr/.
12.8.2 This feature affects exclusively (or almost exclusively
– see 12.8.3) the vowel /ε/, and, of course, only when it is in a
closed syllable and takes a main stress.
Some speakers certainly do, at least on occasion, make a
distinction between, say, mettre /mεtr/ and maître /mε:tr/. In
so far as such a distinction does exist, one has to recognize
that it is phonemic, i.e. that /ε/ and /ε:/ count as separate
phonemes. The number of pairs in which it even can occur is
very small, and may well be limited to the following:
/ε/ /ε:/
belle /bεl/ bêle /bε:l/
bette /bεt/ bête /bε:t/
elle /εl/ aile /ε:l/
faite /fεt/ fête /fε:t/
laide /lεd/ l’aide /lε:d/
lettre /lεtr/ l’être /lε:tr/
mettre /mεtr/ maître /mε:tr/
saine /sεn/ scène, Seine /sε:n/
tette /tεt/ tête /tε:t/
It must be pointed out, however, that the majority of French
speakers do not observe the distinction and, in so far as it
exists at all, it tends to be characteristic of the speech of the
older generation (it is, says Henriette Walter, 1977: 43,
‘d’autant moins vivant que le sujet est plus jeune’). Furthermore,
few (if any) speakers observe it in all the above pairs.