> In all, or at least most (?) dialects of N. American English
> the onset of both /aI/ and /aU/ is raised when they precede a
> voiceless segment or [D] when an allophone of /t/. In Canada
> the onset is both higher and more fronted in /aI/, and higher
> and more backed in /aU/ than in the U.S. Although the same
> tendency appears in some of the northernmost states. To my
> ear it also sounds like the onset of /aU/ is more rounded in
> Canadian English.
This got me to thinking, and I located recordings of Canadian
speech at http://www.yorku.ca/twainweb/troberts/raising.html .
After listening to them carefully, I'm not so sure that the
onset of /aU/ is more backed, as I thought. I assumed this
believing the difference in the U.S. and Canadian diphthongs
to be one of the latter starting in positions closer to their
end points. Nor am I now so sure that a greater degree of
rounding is involved in the onset of the Canadian /aU/. I
came to that conclusion listening to the dialect of Vancouver,
I wonder if which doesn't differ in this respect from that of
Toronto. Can anybody with some expertise in this area, or just
a better ear, help me figure it out?