Physics and psychoacoustics of plucked-string instruments

Roberts, Wiliam 2015. Physics and psychoacoustics of plucked-string instruments. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The overall goal of this work is to help classical guitar makers to have better control over the potential sound of their instruments. This is done by correlating changes in the vibrational behaviour of an instrument with perceivable changes in its radiated sound. Three strategies have been employed in this thesis in an attempt to accomplish this goal. An investigation is carried out on the vibrational properties and radiated sound of a classical guitar, steel-string folk guitar and a five-string banjo. The aim here is to demonstrate how large constructional differences in plucked-string instruments lead to their unique acoustical characteristics. Results demonstrate that effective masses of low-order body modes relative to higher-order ones, internal damping of strings and amount of coupling between strings and the body of an instrument are responsible for the main characteristics of these instruments’ acoustical signatures. The problem of over-coupling a string to the body of a classical guitar is then addressed. Over-coupling creates an uneven tone quality between notes, an effect known as wolf notes. Knowledge of the perceptual threshold of over-coupling, which is found using psychoacoustical tests, can help instrument makers build a strongly radiating instrument without wolf notes. Simple remedies are suggested to minimise the effects of wolf notes on existing guitars in the most effective manner. Finally, the smallest perceivable changes are found in the parameters of a physical model of a classical guitar. The parameters that are responsible for the most perceptually obvious changes are likely to be the most important ones for the maker to control because these are the parameters to which our ears are most sensitive. The effective mass and effective area of low-order modes are studied in detail because these parameters have been identified previously as having a strong influence over the radiated sound from the instrument.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	guitar model; psychoacoustics; synthesis; jnd; musical acoustics; wolf note; coupling; banjo; leakage; admittance
Funders:	EPSRC
Date of First Compliant Deposit:	30 March 2016
Last Modified:	07 Mar 2022 16:40
URI:	https://orca.cardiff.ac.uk/id/eprint/80117

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