Quantifying What You Hear...

[Matt Borland]

Hello,

I'm new to this list, but I was wondering if I could get some 
help/opinions/ideas about the way sound in musical instruments is 
described. Currently I'm doing a masters working with Stephen Birkett 
at the University of Waterloo and one of the big problems we have found 
is the inability to discuss musical acoustics in any quantifiable way 
that has meaning to both musicians and people using a scientific 
approach (not to say that people can't fall into both of those groups 
at the same time). My work is going to involve piano soundboards, but 
before I start on that I want to think about and define some ways to 
describe the sound/tone of the soundboards and pianos I will be 
measuring for vibrational and acoustic properties.  I think we've all 
used words like bright, muddy, crisp, sharp, round, dark, etc. to 
describe the sound of an instrument, but these are highly subjective 
words that are difficult to draw any concrete conclusions from. So the 
question is, are there any other parameters you feel would be useful to 
quantify? Maybe there is a way to measure how "bright" something 
sounds...If you have a concept and some sort of definition to go along 
with it I'd love to hear from you.

Some obvious ones (if these are poorly defined, feel free to redefine 
them) are:

decay time - the time it takes for sound level to decay by a defined 
amount (ie 60dB, or whatever, I'm thinking of the RT60 definition for 
reverberation time from acoustics) linked to sustain
impedance - a measure of opposition to motion of a structure subjected 
to a force
bloom - change in tone over time
response time - is the time a system or functional unit takes to react 
to a given input

Basically I would like to make the link between the frequency and modal 
analysis techniques available with the language that musical 
instruments are discussed in terms of. I really doubt anyone has talked 
about how nice the mode shapes of their pianos are, but maybe if things 
like this are connected to the way they sound by some common definition 
or understanding then they could be used to measure the properties of 
an instrument. I would also like to make the link between these 
techniques and the way we perceive sound and pitch, something that I 
feel has been forgotten in a lot of research work.

Any help or ideas would be greatly appreciated,

Matt Borland