Sine waves are the simplest periodic excitation, and all complex waveforms decompose into them

Evidence

So far we have only considered the propagation of a single disturbance through the golf ball-and-spring model and we have seen that, in this case, the disturbance travels at a constant velocity that is dependent only on the characteristics of the medium. Thus any other type of disturbance, such as a periodic one, would also travel at a constant speed. Figure 1.6 shows the golf ball-and-spring model being excited by a pin attached to a wheel rotating at a constant rate. This will produce a pressure variation as a function of time that is proportional to the sine of the angle of rotation. This is known as a “sinusoidal excitation” and produces a sine wave. It is important because it represents the simplest form of periodic excitation. As we shall see later in the chapter, more complicated waveforms can always be described in terms of these simpler sine waves. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 135

Categorization

• DEFINE: Defines sinusoidal excitation and the fundamental principle that any periodic waveform can be expressed as a sum of sine waves.
• XREF: Fourier’s theorem that any periodic signal decomposes into sinusoidal components; connects to Addendum ‘Grafting & Growth’ analogy of compound structures composed of simple elements. — connects to: Any complex tone is decomposable into sine wave components displayed as a spectrum — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 449