A resonator responds only to the matching Fourier component of a complex wave

Evidence

To put a finer point on it, only sinusoidal sound waves with frequency near f matter most. Suppose a sawtooth wave of frequency f impinges on the resonator. This contains pure sinusoidal partials at frequencies at f, but also at 2f, 3f, … , even though the complex wave overall has frequency f. But the resonator is not resonant near 2f, 3f, and so on, so only the component at frequency f matters. — Eric J. Heller, Why You Hear What You Hear- An…, 1201

Categorization

• XREF: Core to the reader’s question: this is the mechanism by which the ear’s resonant structures pick out single spectral components from complex sound.