An acoustical investigation of the concert harp
Abstract
This thesis is a report of acoustical research on the concert harp.
The harp has an established place in the symphony orchestra and is
reacquiring its role as a solo chamber instrument that it had before the
development of the modern piano.
As far as can be determined, this is the first doctoral thesis on
the concert harp and serves as an introduction to the science of the
instrument, The experimental methods employed- holographic
interferonietry, input admittance measurements, Chiadni glitter pattern
methods, sound pressure level measurements- have all been successfully
used with work on other musical instruments. Theoretical calculations
are used to underpin the experimental results for several of the
subjects reported. The experimental results are also compared with the
results of similar tests on different musical instruments. Analyses of
the violin, guitar and piano are particularly used in discussions.
This work is specifically on the "Orchestra" concert harp,
manufactured and sold by the Salvi Harp organisation, though reference
Is made in Chapter 3 to the "Electra" concert harp, which is also a
Salvi harp. The "Orchestra" harp has a similar design to many other
concert harps built by different luthiers around the world.
This thesis is structured as follows. The first chapter is a review
of historical and contemporary research an stringed musical instruments.
The next chapter is a detailed description of the Salvi "Orchestra"
harps the dimensions of all the inportant features are given, the
tensions and materials of the strings are reported and there is also a
short description on the playing of the instrument.
The next five chapters form the kernal of the research report and
deal with the vibrations of the constituent part of the "Orchestra" and
finally the completed, strung harp itself. In Chapter 3, the vibrations
of the free soundboard are reported in some detail. Analysis is made at
a number of stages of the construction of the soundboard itself. The
position of the neutral axis on the soundboard is also given. There is
also reference to the soundboard of the Salvi "Electra" harp.
Chapter 4 deals with the air resonances in the enclosed air volume
of the "Orchestra" soundbox. Both a Helmholtzian air mode and higher
order air modes are discussed. Theoretical models are used for both
forms of air modes, Chapter 5 is a report of the vibrational modes of
the "Orchestra" soundbox using both Chladni glitter patterns and
holographic interferonietry. The results of Chapter 5 are confirmed and
expanded by the work in Chapter 6, where input admittance measurements
are made on the soundbox.Chapter 7 investigates the vibrational modes of
the soundbox, both in the isolated state and as part of a completed,
strung harp.
This is followed by a chapter on the directivity of the "Orchestra"
harp in which the principal areas of radiation from the harp are
reported. The next chapter deals with attempts to relate objective
measurements with subjective opinions of six concert harps. The last chapter summarises the principal results of the various
analyses reported in this thesis. Suggestions for further research on
the harp are made. There are also suggestions for the improvement of the
Salvi "Orchestra" harp.
There are three appendices at the end of this work. The first deals
with the testing of spruce samples intended for the soundboards of the
harps. The effect of the veneer is also discussed. The second appendix
deals with the production and physical properties of gut harp strings.
The third appendix describes the changes to the resonant modes of an
isolated soundbox produced by changing the shape of the straining and
cover bars of the soundboard.
Type
Thesis, PhD Doctor of Philosophy
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