Acoustical characteristics of glass wool materials in hyperbaric helium-air using transfer function method

The authors have measured normal incident sound absorption coefficients, propagation constant, and characteristic impedance of some glass wool by the "transfer function method." It is found that in a hyperbaric environment, 96K glass wool has larger sound absorption coefficients than a 32K glass wool usually used in normal air. This reason is due to the phenomenon that the 32K glass wool has small attenuation constant in hyperbaric environment. The authors compared propagation constants and characteristic impedance in normal air to in hyperbaric helium-air. The authors have estimated normal incident sound absorption coefficients of the 32K and 96K glass wool in helium-air from those in normal air