A Rayl, rayl or Rayleigh is one of two units of specific acoustic impedance or, equivalently, characteristic acoustic impedance; one an MKS unit, and the other a CGS unit.
A Rayl, rayl, or Rayleigh is a unit of measurement for acoustic impedance, which is a measure of how much sound energy is transmitted through a medium. The two units are based on different systems of measurement: one is based on the MKS system and the other is based on the CGS system.