I just listened to "Amazing Grace" played on Scottish bagpipes
on the CBC. The difference made by idiosincratic scale of that
instrument is dramatic, and to my unsophisticated ear it sounds
"wrong". I believe the tune is being played in its natal scale
on that instrument, however!
Certainly scales are, in part, cultural. I am delighted with
the quality of the contributions to this thread. It should
serve to dispel many myths about pitch widely held by physics
teachers. I believe that physics teachers who don't know what
they are talking about can do great harm to the public image of
science in general. Making incorrect pronouncements about pitch
and scales to an audience which includes people who can detect
the errors, and who are not themselves scientists, will lead to
a richly deserved loss of reputation - for the speaker, and for
science in general.
Anyway, I learned a lot, including the pointers to some useful
material on the web. I'm thinking of reviving my old Physics of
Music course and pitching it to the Department for my post-
retirement project. It won't pay much (C$5,000 = US$3400) for
39 lectures, but it will be fun to see what materials I can
find and what new stuff I can learn on this topic.