A Rayl is a unit of acoustic impedence and has the same name when using a CGS or MKS definition.

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 pressure and the particle velocity it produces. The impedance is 1 rayl if unit pressure produces unit velocity.

In MKS units, this means 1 rayl equals 1 pascal-second per meter (Pa·s/m), or (equivalently) 1 newton-second per cubic meter (N·s/m3).

In CGS units, 1 rayle equals 1 dyne-second per cubic centimeter (dyn·s/cm3). The CGS rayl equals 10 MKS rayls.

The units are named for Robert John Strutt, 4th Baron Rayleigh (1875-1947).

External links

• Dictionary of Physics Units of Measurement
• A discussion of the history and ambiguity of the rayl