Instrument sound equals input spectrum multiplied by body response
Evidence
The output spectrum is derived by multiplying the amplitude of each component of the input spectrum by the response of the body of the instrument at that frequency. In the figure, this mul tiplication becomes an addition since the amplitudes are expressed logarithmically as dB values, and adding logarithms of numbers is mathematically equivalent to multiplying the numbers themselves. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1150
Note that the frequency scales are logarithmic, and therefore the harmonics in the input and output spectra bunch together at high frequencies. The output spectrum is derived by multiplying the amplitude of each component of the input spectrum by the response of the body of the instrument at that frequency. In the figure, this multiplication becomes an addition since the amplitudes are expressed logarithmically as dB values, and adding logarithms of numbers is mathematically equivalent to multiplying the numbers themselves. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1125
Categorization
- XREF: The source-filter / transfer-function model mirrors how the reader has thought about soundscapes as signal-and-modifier systems in prior chapters.
- DEFINE: Explains the multiplicative filter model of instrument radiation, a core concept in psychoacoustics.
- corroborated: 2 independent passages support this claim — David Howard, Jamie Angus, coustics and Psychoacoustics, 1150; David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1125