Porky wrote:


If we get into Doppler shift due to motion in air molecules, I suspect
we're getting down to "the bumble bee doesn't really fly because the math
says it can't" point.

Huh? That's exactly what Doppler distortion is due to.
There is a mild non-linear relationship everywhere in a
soundfield between particle velocity about a point and the
fluid velocity at that point. That was my epiphany. Not
much as epiphanies go but, hey, they get fewer and fewer
every year. :-)

If the equations show that all that much Doppler distortion in a speaker,
why can't we hear it?

Who says we can't? It's sorta hard to get rid of to do an
ABX test on.

By Occam's Rasor, either our hearing mechanism has built in compensation,
so Doppler distortion doesn't matter, or the math is wrong and it needs to
be revised. That isn't to say that it doesn't happen in the
piston-in-an-infinite-tube model, it just means that the speaker/room model
is a totally different animal.

Sure it is but it should get signifigantly worse with a
driver in an enclosure rather than in a tube because of the
large excursions demanded at the low frequencies to couple
anything from an enclosed speaker to a room. You can get
real high SPL low frequencies in a tube without much
excursion, which is what causes it, but not so with an
enclosed speaker in a room. You have to push a whole lot of
LF air up close to get what's in the signal to reach you at
any distance.

Dunno what you mean by built in compensation nor why there
would be anything like that. It's not the kind of thing
evolution would have devoted much energy to. There weren't
many broadband sound sources to work with even if it had
been deemed important for some reason.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein