Hi John,  Read your MMD item with great interest.  I worked at the
Deafness Research Lab at Los Angeles Children's hospital from 1958 to
1965, and vaguely recall something like what you reported.  Perhaps it
will come back to me when my memory gets 'refreshed'.

I am an amateur radio operator (since 1947) and ex-navy radioman and
have spent many hours with headphones listening to weak and strong
signals, and have never noticed the effect you describe.  However, in
talks with a musician friend about perfect pitch, I recently discovered
that I suffer from a condition called diplocousis.  When I switched
my headphone from one ear to the other the pitch changed (only a few
cents, but noticeable)!  I have confirmed this several times, and weeks
later, to see if it was a temporary effect.  I plan to measure the
difference using my Strobo-Conn.  It does not affect my listening
enjoyment.

My ears are also different.  I hear low frequency best with my left ear,
and highs with the right!  I just tuned my piano using a combination of
Strobo-Conn and by ear, and can hear the pitch change as I turn my
head, favoring one ear or the other.  But beats don't change, and
I doubt any problem tuning.

An audiologist probably can answer.

John Spradley in Sylmar, California