A healthy cochlea emits new frequencies when stimulated by two tones

Evidence

Distortion-product otoacoustic emissions (DPOAEs), in turn, are measured with two tones that differ in frequency, for which a normally functioning cochlea responds with an emission in additional frequencies. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 2727

Categorization

• DEFINE: Defines what distortion-product otoacoustic emissions are and how they are measured.
• CANDY: A fun fact: the inner ear itself emits sound in response to two-tone stimulation — a genuinely counterintuitive biological detail.