Ron Chaplin wrote:

>Hearing this work started me wondering just when dissonance began to be
>used as a means of expression.

 From the scientific point of view, I think acousticians would say that
for any interval other than unison and octave there is no such thing as
absolute consonance or dissonance: it is a matter of degree, perception
and opinion.

A musician however might say that the concept of dissonance arises out of
the concepts of harmony and counterpoint. It is possible, though unusual,
to have harmony without counterpoint, but impossible to have counterpoint
without harmony. Even where there is only a single line of melody, as for
example in plainchant, there can be dissonance, if only because as we hear
each note the previous note may not have completely died away, and even if
it has we retain it in memory as we hear the next note.  Where two or more
pitches sound at the same time the dissonance of the resulting sound as
perceived by different listeners could be anything from zero to maximum,
and some combinations might appear more dissonant than others. Dissonance
is a relative and comparative perception, not an absolute.

Also, the idea of what harmony is consonant and what dissonant varies
across the globe and from one era to another. To those of us thoroughly
accustomed to classical harmony, very early music may sound dissonant,
though it was not so intended at the time, as may more recent pentatonic,
dodecaphonic or atonal music, which again may not be so intended. The whole
thing is very hard to pin down. Very easy pieces, such as a child is taught
to play in the earliest piano lessons, are probably not going to seem
dissonant -- but then they quickly become boring because they seem so
bland. In fact without dissonance all music quickly becomes very boring.
This can be demonstrated by listening through headphones to "pure"
electronic "music" generated without harmonics or upper partials. The
complexities of timbre and dissonance, and factors such as attack and
decay, are like the condiments that stimulate the appetite and the
digestive juices and bring out the true flavour of the meal.

So it seems to me that it is not a question of dissonance being "used as
a means of expression", as if it was an add-on effect like crescendo or
staccato. It can of course sometimes be used in that way, where for example
the composer deliberately introduces discords in order to depict something
like a struggle or a storm. But I believe that in music as in all art, how
you say it is inseparable from what you are saying. Hence 'wrong-note
harmony' in fact sounds right.

Then of course there's the question of unpitched instruments through the
ages. Technically dissonant because they are not consonant with any pitch,
they nevertheless seem to fit in with whatever else is playing.  You cannot
make a triangle or tambourine sound out of tune. Go figure.

Alan Moss