Rayleigh disk

noun Acoustics, Mechanics.

a small circular disk, usually of mica, that is suspended from a fiber and tends to be deflected at right angles to a stream of air, indicating by its deflection the intensity of a sound wave.

Origin of Rayleigh disk

First recorded in 1910–15; named after J. W. S. Rayleigh
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019