I reckon it'd be better to split the whole thing into three entries.
Whether an instrument transposes or not has nothing to do with concert pitch.
Here's my rough try at the three entries:
Concert Pitch:
Notes like a, b, c etc., describe a relationship between themselves,
not an absolute pitch. The nature of the relationship is the
so-called temperament (q.v.). To be in tune, a group instruments must agree
on the relationship between pitches *and* the absolute pitch of one of
the notes. In recent times that pitch, `concert pitch' has been
defined as 440Hz for the A above middle C, with other notes arranged
according to the temperament being used.
Temperament: the relationship between different pitches in a scale.
In the simplest case, an *equal-tempered* system has notes whose
frequencies are in the ratio of the twelfth root of two. Such a
system always sounds out-of-tune, because thirds, fourths and fifths
are not exact ratios. However it is widely used because all notes are
equally spaced, regardless of the starting note of a scale.
Transposing Instrument: If an instrument is usually notated at a
pitch other than its sounding pitch (whether out of tradition, or for
the convenience of the player) it is said to be a *transposing
instrument.* Bes and A Clarinets, many brass instruments, and some saxophones
are transposing instruments.
--
Dr Peter Chubb http://www.gelato.unsw.edu.au peterc AT gelato.unsw.edu.au
http://www.ertos.nicta.com.au ERTOS within National ICT Australia
A university is a non-profit organisation only in the sense that it
spends everything it gets ... Luca Turin.