Audio-frequency surface wave characteristics above porous and comb-like surfaces

Part of the solution for sound field due to a point source in air over porous boundary has form an airborne surface wave. Analytical expressions wave characteristics are reviewed and corresponding analytical group speed obtained from thin layer approximation impedance comb-like surface, two approximate models acoustical properties media model identical slanted slit pores. Predictions absorption coefficient spectra hard-backed with flow resistivity sufficiently low that there is extended reaction made using compared those relatively exact pore model. The derived specifically predict asphalt found be least satisfactory. various used obtain analytic speed. including velocity data arrays parallel aluminium strips.