An acoustical investigation of the concert harp

Vibration;Sound;Sound waves

Bell, Alexander J. ; Firth, Ian M. ; Firth, Ian M.

University:University of St Andrews

Department:Physics & Astronomy (School of)

关键词: Vibration;    Sound;    Sound waves;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/2768/AlexanderJamesBellPhDThesis.pdf?sequence=3&isAllowed=y

来源: DR-NTU

【 摘 要 】

This thesis is a report of acoustical research on the concert harp.The harp has an established place in the symphony orchestra and isreacquiring its role as a solo chamber instrument that it had before thedevelopment of the modern piano.As far as can be determined, this is the first doctoral thesis onthe concert harp and serves as an introduction to the science of theinstrument, The experimental methods employed- holographicinterferonietry, input admittance measurements, Chiadni glitter patternmethods, sound pressure level measurements- have all been successfullyused with work on other musical instruments. Theoretical calculationsare used to underpin the experimental results for several of thesubjects reported. The experimental results are also compared with theresults of similar tests on different musical instruments. Analyses ofthe 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 referenceIs made in Chapter 3 to the "Electra" concert harp, which is also aSalvi harp. The "Orchestra" harp has a similar design to many otherconcert harps built by different luthiers around the world.This thesis is structured as follows. The first chapter is a reviewof 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, thetensions and materials of the strings are reported and there is also ashort description on the playing of the instrument.The next five chapters form the kernal of the research report anddeal with the vibrations of the constituent part of the "Orchestra" andfinally the completed, strung harp itself. In Chapter 3, the vibrationsof the free soundboard are reported in some detail. Analysis is made ata number of stages of the construction of the soundboard itself. Theposition of the neutral axis on the soundboard is also given. There isalso reference to the soundboard of the Salvi "Electra" harp.Chapter 4 deals with the air resonances in the enclosed air volumeof the "Orchestra" soundbox. Both a Helmholtzian air mode and higherorder air modes are discussed. Theoretical models are used for bothforms of air modes, Chapter 5 is a report of the vibrational modes ofthe "Orchestra" soundbox using both Chladni glitter patterns andholographic interferonietry. The results of Chapter 5 are confirmed andexpanded by the work in Chapter 6, where input admittance measurementsare made on the soundbox.Chapter 7 investigates the vibrational modes ofthe 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 arereported. The next chapter deals with attempts to relate objectivemeasurements with subjective opinions of six concert harps. The last chapter summarises the principal results of the variousanalyses reported in this thesis. Suggestions for further research onthe harp are made. There are also suggestions for the improvement of theSalvi "Orchestra" harp.There are three appendices at the end of this work. The first dealswith the testing of spruce samples intended for the soundboards of theharps. The effect of the veneer is also discussed. The second appendixdeals with the production and physical properties of gut harp strings.The third appendix describes the changes to the resonant modes of anisolated soundbox produced by changing the shape of the straining andcover bars of the soundboard.