In this chapter, we will look at a miscellany of musical performance and musical instruments that all involve impacts of one kind or another. The chapter begins with some background discussion on how vibration can be excited by one structure bouncing off another one. Then section 12.2 looks at stringed instruments excited by bouncing: the hammered dulcimer and its relatives around the world, the piano, and finally the clavichord.
Section 12.3 broaches a different topic: buzzing. In many musical contexts a buzz is a bad thing — it might be an indication of a glue joint coming unstuck, or it might be a fret buzz caused by incorrect adjustment of a guitar fingerboard. But in some cases, buzzing is deliberately used as a musical resource. The hurdy-gurdy often has a buzzing bridge which can be used to provide rhythmic emphasis in performance. Even more strikingly, Indian instruments like the sitar and tanpura have a special design of bridge which induces subtle but persistent buzzing and gives these instruments their characteristic sound quality.
Section 12.4 look at something quite different: church bells. The sound and handling properties of church bells depend on the complicated way that the clapper interacts with the bell during ringing.
The idea for this chapter was first suggested by Evan Davis, who also contributed insights into drumming and much other useful feedback. The material on the clavichord was first explored in the course of a student project by William Layzell-Smith [1]. I am grateful to Dan Tidhar for giving us access to a clavichord, harpsichord and spinet for the purposes of measurements.
[1] William Layzell-Smith, “An investigation of the acoustic vibrations in different keyboard instruments”, MEng dissertation, Cambridge University Engineering Department (2021).