|MadSci Network: Physics|
Hello, There are 2 main ways in which sound can make its way from one room into another: 1. Airborne. Through leaks (around doors, windows, air ducts). This is the main cause of sound leakage and is often underestimated. Have gaskets around doors and windows. Air ducts are tougher. Unless you can periodically close it, the duct should have a padded labyrinth in it - not something you can do in an existing building 2. Structure-borne. This means sound hitting a wall causing the wall to vibrate (i.e. a sound wave within the solid structure). Sound waves propagate much easier through solids than through air, which explains why sounds inside some buildings can be heard many floors up or down from the source. What decreases the sound level is the percentage of acoustic energy that makes it across boundary between media (air and solid). The larger the difference in mass between the media, the more difficult it will be for a sound wave to enter from one medium into another. Simply put: the heavier the wall, the better it will stop sound. As you can also see from the above reasoning it is more effective to have more than 1 transition, as energy is lost every time. This can be done using a double wall (optionally with padding in-between). Of course, the walls normally share a common base (all solid) through which some of the sound will still penetrate. If you really want this degree of isolation, a "room within a room" sitting on springs is the ideal solution. A somewhat expensive and impractical one. In case of the glass wall, use two or three medium-thickness (0.2") sheets of glass with air spacing (0.4" to 2")between them. Make sure no humidity gets in-between there (nothing to do with the sound of course). Alternatively, use 2 double-glass windows fitted to either side of the wall. Kind regards, Bruno
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