In our experience ceiling and wall assemblies, can be the main pathways for the two main types of sound transmission. The first type is the airborne sound – such as loud music) and the second is impact sound, such as footfalls on the floor above.
If the ceiling and wall assemblies have been designed and constructed to provide adequate airborne isolation, impact noise can still be a problem. If the finished floor surface has been designed to accommodate carpeting, the carpeting and under pad will normally provide a good degree of impact sound isolation. On the other hand, if the finished floor is floor is constructed in hardwood, stone or ceramic tile. Achieving good impact sound isolation requires much more attention at the design stage to prevent potential sound test failures.
One of the main misconceptions is sound simply passes through materials, this is not the case. Sound waves are form of energy that energises any material that the sound waves come in contact with. Thus sound energy that impacts on a wall for floor/ceiling assembly will cause the material to vibrate like a radio speaker; the energised material then becomes the transmitter of the sound energy.
Thinner, more lightweight building materials often hold the key to effective noise control, by using materials with different acoustical characteristics that will dissipate and diffuse the sound energy. Insulation in the cavity converts some of the energy in to heat while a resilient channel will help minimise the direct connection of the gypsum board from one side of the assembly to the other. Each material and its relationship to one another, produces small increases in sound isolation that in turn reduces the transmission of sound through the whole system and subsequently improves the sound insulation characteristics of the acoustic partitions.
I hope the above article helps to explain the importance material selection within acoustic design. If you would like more information or some acoustic design advice on your project, please don’t hesitate to contact me on firstname.lastname@example.org or call me on 07775623464.