Influence of Gas Filling on the Sound Isolation of Glass Insulating Panes

Through gas filling the sound isolation of insulations glass panes is improved in the middle and higher frequencies. The overall effect arises from various effects, from a lowering of the sound level in the pane-cavity and from modifying the excitation and radiation of the second pane. By the use of heavy gases the sound level in the cavity is diminished because the free waves in the cavity are essentially weaker than in the case of air. The filling of gas therefore acts similarly to filling the cavity with a sound absorbing material.

The light gases become positively excited through the anomalous well-known effect of flexurally excited plates when λ _G > λ _L. In both cases at middle and higher frequencies, for different physical reasons, there is a reduction of the stiffness of the pane-cavity from 10 to 20 dB compared with an air filling. The favorable effect of filling with gas is limited at high frequencies by the solid-borne transmission through the stiff bonding of the isolating glass-panes at their edges. More significantly for practical application a gas-filling is inaffective at low frequencies, as soon as the dimensions of the panes are small compared with the wavelength λ _L of sound.