ガスを封入した二重ガラスの音響透過損失

抄録

Sound transmission loss (TL) of double glazed panels with different gases in the cavity was measured using the two room transmission suite method. Five kinds of gases were used in the experiment: freon, helium, the mixed gas of air and helium, etc.. In addition, the calculation of TL was carried out based on the distributed constant circuit theory, which showed similar frequency characteristics to the experimental result. Valuable informations about the refraction and the propagation of sound through the intervening gas space were obtained from the experimental and the calculated results.
The double panels filled with freon in the cavity, in which sound velocity was lower than that in air, provided a sharp reduction in TL generated by the double-wall resonance (wall-gas-wall). In the frequency range higher than the resonance frequency, TL was much greater than that of the double panel filled with air in the cavity. This characteristic was due to the intensification of the resonance caused by the sound refraction.
For the case in which the cavity was filled with helium, the sound velocity was higher than that in air. This case provided greater TL in a wide frequency range. This was probably due to the mitigation of double-wall resonance and the total reflection of sound on the incident-side wall.