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Whitehouse, James W. and Sharp, David B.
(2007).
URL: http://acoustics.open.ac.uk/802574C70048F266/(http...
Abstract
The question of whether the material of construction perceptibly affects the timbre of a lip-reed instrument has been the subject of much discussion. In this paper, to establish whether any differences in timbre can be correlated with variations in wall vibration amplitude, five post horns of identical geometry and surface finish but manufactured from different copper alloys are studied. Mounting each post horn, in turn, vertically on a turntable, enabled vibration measurements to be made at discrete locations around the circumference and along the length of each instrument. First, the frequencies and shapes
of the structural resonances of the post horns were established by mechanically exciting the post horn under test through a set frequency range and using a laser Doppler
vibrometer to measure the wall vibration amplitudes. An artificial mouth was then used to blow each post horn, the notes produced were recorded and the vibration amplitudes
induced under playing conditions were measured using the vibrometer. The wall vibrations induced when the post horns were artificially blown are compared with each other and then related to the structural responses of the instrument. In addition, preliminary results are presented from both spectral and psychoacoustical analysis of the notes produced by each post horn.