Quantifying What You Hear...

[Karl kaputt]

Matt,

very interessting question. I am psychologist and did two work experiences 
in the field of psychoacoustics, one of these at the Daimler Benz AG 
(Mercedes), the other at SASS, the company of Prof. Rudolph Bisping. Indeed, 
the only way to combine objective with subjective desprictions is to test 
many many subjects.

The situation of cars and intstruments is similiar because of its dynamic 
and not static state. Prof. Bisping argues that there are several levels:
-acoustic (=physical like dB, spectum......)
-psychoacoustic (loudness, tonality, roughness, sharpness, 
impulse-perception, consonance, contrast......)
-emotional (fun, sympathy, surprise....)
-cognitive (verbal classification, coping, wishes, thoughts, anticipations)
-behavioural (motor activity, psychophysical reaction and to buy or not to 
buy a Mercedes!)

Almost all car companies have psychoacoustic departments. They give subjects 
different sounds (artificial or real car sounds) and let these rate by 
subjects. If artificial: they modify the sounds by computers and look at the 
psychoacoustic (ie subjective) outcome. So, every company should have own 
databases with correlations between physical and psychological measurements, 
but I am shure that the results won´t be published!

An interessting approach comes from Bismark. He developed a schema to 
calculate the "feeling of good sound" (in terms of sharpness) from the 
spectral analysis:

Bismarck, G. von; Sharpness as an attribute of the timbre of steady sounds. 
Acoustica 28 (1974), 159.

E. Terhardt and G. Stoll correlated subjective with other subjective 
measures. They found that "good sound" depends on roughness (see Helmholtz), 
sharpness (Bismarck) and tonality.

Hope that helps. A good source for further research might be the journal 
Acoustica.

Gregor


>From: Matt Borland <mattborland at gmail.com>
>Reply-To: Pianotech List <pianotech at ptg.org>
>To: pianotech at ptg.org
>Subject: Quantifying What You Hear...
>Date: Fri, 29 Dec 2006 19:37:07 -0500
>
>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
>

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