RESUMO
The attenuation coefficient and phase velocity of plane sound waves propagating in three perpendicular directions in glass wool were measured in the frequency range 50-10,000 Hz. For glass wool of mass density 14 kg/m3 at the frequency 1,000 Hz, the attenuation constant for propagation perpendicular to the glass wool sheets was 75 dB/m, and for propagation parallel with the sheets 57 dB/m. For mass density 30 kg/m3, the corresponding numbers were 140 and 100 dB/m. The measured values were compared with calculated ones taking into account the movements of the fiber skeleton. The calculations need the elastic moduli, which were measured. For density 14 kg/m3 and deformation perpendicular to the glass wool sheets, the static modulus was 2.0 kPa, and for parallel deformation 120 kPa. The corresponding numbers for mass density 30 kg/m3 were 16 and 390 kPa.
