Rayl

A rayl is one of two units of specific 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 specific impedance is the ratio between the sound pressure and the particle velocity it produces.

The specific impedance is one rayl if unit pressure produces unit velocity.

The units are named after John William Strutt, 3rd Baron Rayleigh (12 November 1842 – 30 June 1919).

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.

References

T. D. Rossing, Springer Handbook of Acoustics, Springer, 2007, p. 60

L. E. Kinsler, A. R. Frey, A. B. Coppens, and J. V. Sanders, Fundamentals of Acoustics, Fourth Edition (New York: John Wiley & Sons, Inc.,2000), p. 126

mks rayl =10 x cgs rayl (beranek acoustics 1954)

External links

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