"Mark Simonetti" wrote in message

Of course it will. And its instanteious velocity is added to the
instantaneous velocity due to the upper note.

Okay, but it seems like people are saying that this isn't the case,
and is the reason doppler distortion would NOT occur, which seems
plain bizzare, IMHO.

So bizarre, that it is in fact fallacious.

Surely, as the lower frequency moves the cone
back and forth, which at the same time is vibrating to create the
higher frequency, that is IDENTICAL to moving a single vibrating
source back and forth, like the train analogy (except the train
doesn't move back and forth unless the driver is very confused).

Agreed.

Therefore, the doppler effect surely DOES occur.

Agreed.

It just seems really obvious, so I must be missing the whole point of
this, I'm no physics scientist !

I've got two years of physics, an undergraduate degree in engineering and
completed most of my MSE except for my thesis project (wife's pregnancy
ended that). I've also measured it quite conclusively in the lab. I've been
reading papers about it for like 30 years in the JAES and JASA. Yes, I think
that Doppler distortion exist in speakers, but no I don't think it is a
serious issue. In contrast the AM distortion in speakers is a very serious,
audible issue.