This page describes the research I did while I was working in the Acoustics group at Edinburgh University (Dept. Physics and Astronomy, Kings' Buildings, University of Edinburgh, Mayfield Road, EH9 3JZ). The research looked at how physical characteristics of some wind instruments affected their sound quality.
Before coming to Edinburgh, I did a PhD at Cardiff on the acoustics of the classical guitar. If you are interested you can read a summary of my research on the classical guitar. You can also download my thesis and hear some examples of guitar sounds synthesised from the computer model I developed.
You may also be interested to look at my list of scientific publications.
Visit the Edinburgh University Fluids and Acoustics Group Home Page to find out more about past and present research work carried out there.
My research project is on the psychoacoustical analysis of wind instruments, particularly those classified as "lip-reed" instruments, such as the trumpet and trombone. We are interested in finding out which physical features of the instrument have the most significant effect on the perceived sound quality of the instrument.
Experimental work and computer modelling can be used to examine the relationships between physical properties of an instrument (materials, dimensions, shape) and the behaviour of the instrument, which can be assessed, in the case of wind instruments, by measuring an input impedance curve. Such work can show how differences in the materials or design used to make an instrument can lead to differences in its physical behaviour. For example, measurements made on two trombones made to the same design but using different materials might show up differences in the peaks observed on the input impedance curves. These differences might correspond to changes in the amplitudes or Q-values of the normal modes excited in the air column. This is fine in itself, but doesn't tell us anything about the sound qualities of the two instruments.
The function of a musical instrument is, of course, to allow a player to produce musically pleasing sounds. The important question, from a musician's point of view, would be: what is the difference in sound of the two trombones? Psychoacoustical work, which examines subjective attributes such as pitch, loudness and timbre, provides a means of linking subjective musical judgements of an instrument's sound with physical measurements, such as frequency response curves. The perceptual significance and the musical desirability of particular changes to an instrument's physical behaviour cannot be assessed without careful psychoacoustical work.
I have started my work by investigating the effect on sound quality of using different mouthpieces on the same instrument. I have made some recordings of a cornett in an anechoic environment. Three different mouthpieces were used, and notes at two pitches were recorded. A pitch meter was used to ensure that the pitch of the notes remained constant when the mouthpiece was changed. The sounds were then processed so that their lengths and loudnesses were made equal. I will shortly be doing some psychoacoustical tests with these sounds to determine whether people can reliably identify the notes played with the same mouthpiece and those played using different mouthpieces.
When a player plays the same note several times, the partial spectrum will not be exactly the same each time; variations of at least one or two decibels in the partial amplitudes are to be expected. The kind of changes in tone that a different mouthpiece causes tend to be rather subtle, amounting to a few dB in a small number partials. The results of the psychoacoustical tests will show the amount by which the partial amplitudes must be changed before distinct changes in tone quality are perceived by the listener.
Last updated: October 2011
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