Pitch, Timbre and Off-stage Trumpets (Roger Watt )

Subject: Pitch, Timbre and Off-stage Trumpets
From:    Roger Watt  <watt(at)COMPSCI.STIRLING.AC.UK>
Date:    Fri, 19 Nov 1993 10:39:55 GMT

Please excuse an amateur joining in the debate on pitch.
I have found it fascinating and very similar to the
pre-occupations in my area (vision).

Orchestral trumpets players (I have been one in the past)
all know that a trumpet that is played off-stage (ie. a
long way away from the orchestra -- say up to 50m) sounds
very flat, by as much as a quarter of a tone which is the
limit of tuning on a standard trumpet.

It is easy enough to come up with very cognitive accounts
of this, but can anyone suggest a psychoacoustical account?

Obviously, an offstage trumpet sounds different in quality
(does this count as timbre ?) because it is subjected to a
different set of surfaces to reflect or absorb the frequency
components.  It is also clear that these physical effects are
linear and can't change frequencies, only the amplitudes of
frequencies.  Hence, a psychoacoustical account must involve
a relationship between pitch and the spectral envelope (which
is what I have understood by the tritone story).  At this point
I run out of steam --- a quarter of a tone is not quite as
large as one would have liked for an explanation along
these lines.

Roger Watt
Psychology Department
Stirling University, Scotland