Diphthongs

In a message dated 10/4/01 2:43:07 PM, scooter@BUSER.NET writes:

<< A question to the list, though - is this essentially diphthong creation?
Simafira has five vowels, and, depending on the exact definition of a
diphthong,
which I don't know, it either has no diphthongs, or 25 of them.  The sounds in
fact follow logically; [a] + [i] ==> [ai], with as little glide as possible in
between.  (Though I am working on a glottal stop inserted to set apart some
prefixes, but that's a grammatic construct.) >>

    The "official" indication that there is a diphthong is if you start at
one place and end up at another before releasing the vowel (or, if you have
the right equipment, if the vowel sounds different backwards than it does
forwards).
    In my opinion, [ai] is a diphthong, HOWEVER, [aj] is a much shorter
diphthong, such that it's easier to be thought of as one sound rather than
two, whereas [ai] could be thought of as two.  If you put glottal stops in
between the vowels than there's no question; it's not a diphthong.  A good
way to tell which you have is to lengthen it.  If you lengthen [aj], you'll
end up with [a:j] with a very short release.  If you lengthen [ai], however
my suspicion is that you'd get [a:i:], because both members are significant.
[j] is just a sort of coloring on [a] in [aj], and that's what I personally
was going for in Mbasa, which is why I wrote that way instead of [ai].  What
do you think?  How does it sound to you?

-David