Sound attenuation coefficient, relationship

Since sound speed is a frequency dependent complex quantity, it therefore follows that the characteristic impedance of the media will also be frequency dependent and complex. If the frequency dependence of sound speed is not known, it can be estimated from the attenuation coefficient as follows. For the rubber composites of interest here, usually a A is essentially independent of frequency. Using Kramers-Kronig relationships (5) it can then be shown that ... 

Based on the acoustic equations, Millikan s formula for the drag of droplets and the transport matrix for heat and mass transfer between droplets and their surrounding vapour, a numerical solution for the sound attenuation is given and the influences of droplet size and the evaporation coefficient are discussed. A simplified relationship for the sound damping is suggested which reveals 3 typical relaxation times characterizing the dependence of sound attenuation on the sound frequency. 

When a sound wave is incident upon a textile layer, some of it will be reflected back to the incidence media and some will be transmitted through the textile layer. The fraction of incident energy that is transmitted is termed the transmission coefficient t. If there is no other path for energy dissipation or reflections, the relationship between the transmission coefficient and the attenuation coefficient is ... 

---