is one of two units of acoustic impedance
. When sound waves pass through any physical substance the pressure of the waves causes the particles of the substance to move. The sound impedance is the ratio between the sound pressure
and the particle velocity
it produces. The impedance is one rayl if unit pressure produces unit velocity.
The units are named for Robert John Strutt, 4th Baron Rayleigh (1875–1947). They have the same name when using either the CGS definition or the MKS-based definition, but not the same value:
- In MKS units, 1 rayl equals 1 pascal-second per meter (Pa·s·m−1), or equivalently 1 newton-second per cubic meter (N·s·m−3). In SI base units, that’s kg∙s−1∙m−2.
- In CGS units, 1 rayl equals 1 dyne-second per cubic centimeter (dyn·s·cm−3).
1 CGS rayl = 10 MKS rayls.