Musical instruments
24 Overview: Musical instruments
How do musical instruments work? How can they take a seemingly unmusical input- like a pluck, the buzz of a reed or the scratch of horsehair against a metal string- and turn the input into musical sound? Why are there families of instruments (like violins, violas, cellos and basses) that sound similar? Why do larger musical instruments make generally lower pitches? Why do musical instruments almost always produce several frequencies at once, rather than pure tone?
This part of the book explores how musicians control the properties of simple systems like strings and columns of air to control the pitch of the sounds they produce. New concepts- natural frequency, standing waves and resonance- go a long way to explaining many of the questions in the previous paragraph. Two physical systems commonly used in musical instruments- strings and air columns- will be explored in detail.
This chapter builds on the key relationship among frequency, wavelength and wave speed ([latex]v=f\lambda[/latex]), with wavelength playing the central role.
Musical Instruments: Learning Objectives
- Explain the connection between instrument size and the frequencies of sound produced.
- Describe a standing wave. Define node and antinode.
- Use a standing waves model to explain how string instruments control pitch
- Use a standing waves model to explain how wind instruments control pitch
- Use standing wave model to explain the presence of overtones in musical sounds
- Use standing waves model to solve problems related to string instruments and wind instruments.
- Explain the relationship between forced vibrations and resonance.
- Describe relationship between resonance and standing waves.
- Distinguish between resonant and non-resonant amplification
- Describe a Helmholtz resonator and describe difference between Helmholtz resonator and air column.