The sinusoid-to-pure-tone link is the one stable pillar of pitch perception.

Evidence

The importance of the connection between sinusoidal waveforms and the pure tones—single partials—cannot be overemphasized; it is the one fixed boulder among many rolling stones in the field of pitch perception. It was Ohm who made this connection explicit. Helmholtz gave it legitimacy by making the connection a centerpiece of his work. — Eric J. Heller, Why You Hear What You Hear- An…, 2044

Categorization

• XREF: Anchor for the reader’s why-question: this fixed relationship grounds everything else in auditory theory.