A physical impulse excites all frequencies equally in struck instruments
Evidence
The spectrum of a single impulse is continuous since it is non-periodic (i.e., it never repeats), and all frequency components are present. Therefore any instrument which is struck is excited by an acoustic sound source of short duration in which all frequencies are present. All modes that the instrument can support will be excited, and each will respond in the same way that the plucked reed vibrates as illustrated in Figure 4.21. The narrower the fre quency band of the mode, the longer it will “ring” for. (One useful analogy is the impulse provided if a parent pushes a child on a swing just once. The child will swing back and forth at the natural frequency of the swing and child, and the amplitude of the swinging will gradually diminish. A graph of swing position against time would be similar to the time response for the hard reed plotted in Figure 4.21.) — David Howard, Jamie Angus, coustics and Psychoacoustics, 1290
Categorization
- DEFINE: Explains what an impulse source means acoustically: continuous spectrum, all modes excited — foundational concept for understanding struck percussion.
- XREF: connects to: A hammer strike excites every mode an instrument can support simultaneously — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1266; Impulse responses of real-world acoustic systems drive musical sound — Eric J. Heller, Why You Hear What You Hear- An…, 1122; Continuous-excitation instruments like flutes attack slowly while impulse-excited ones do not — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 689 (+1 more)
Broader Connections
- A hammer strike excites every mode an instrument can support simultaneously
#corroborates(1.00) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1266 - A sharp impulse carries all frequencies at once and yields the full power spectrum.
#corroborates(0.95) — Eric J. Heller, Why You Hear What You Hear- An…, 1067 - Impulse responses of real-world acoustic systems drive musical sound
#expands(0.75) — Eric J. Heller, Why You Hear What You Hear- An…, 1122 - Continuous-excitation instruments like flutes attack slowly while impulse-excited ones do not
#expands(0.72) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 689