Acoustic problems are common in all types of buildings. The term acoustics generally refers to the behaviour of sound within a space and can be divided into two main areas. The first area concerns reverberation of sound produced within a space, which affects the quality and therefore enjoyment of that sound. This concern is most relevant to the design of theatres, cinemas, lecture theatres and the like, though might also be important in the design of a home theatre or similar. Although in these instances the quality of noise within the space is the main concern, keeping external noise out is also important. The issues faced in theatre design are much more complex than those faced by the designer of a home or apartment, but the principles of noise reduction are essentially the same.
In a home the biggest concern is what is known as acoustic separation. This means preventing noise from passing from one space to another, whether it’s about reducing noise transmission between two rooms within the same residence, between adjacent dwellings or between the street and a residence. Obviously bedrooms are the most sensitive areas, though it can be just as crucial to reduce noise disturbance in offices and media rooms.
The quest for a good night’s sleep has been the driving factor behind many recent developments in acoustic technology. Residents in aircraft noise zones are particularly aware of the issues surrounding noise transmission. The best way to reduce noise transmission is to eliminate gaps. The main principle in noise reduction is to eliminate all paths for noise to travel. Noise travels well through open space, so open windows or doors, or poor seals, will allow the vibrations to pass through. The next step is to select materials that reflect noise. In general, the harder and denser the material the better it will be at stopping noise. Brick, for example, is better than timber.
If you are aiming to control reverberation (or echo) in a space you will need to look at the absorption characteristics of internal finishes. Soft, porous materials such as curtains, carpet and textured wall or ceiling panels are highly effective in absorbing and controlling noise. Once again, however, if you are seeking to prevent noise passing from this space to another you will need to combine the absorbent materials with hard, reflective materials behind. The absorbent materials alone will not effectively stop noise from being transmitted.
Vibration noise is another issue. Disturbance due to footfall from one floor to the one below can be a big problem in multi-storey buildings, especially apartments. Timber or steel floor structures with sheet flooring are the worst culprits due to vibrations passing easily through the structure. Acoustic blankets or cushions can be installed between the floorboards and structure to absorb vibrations. It also makes sense to fill the floor cavity with acoustic insulation and use an additional layer of dense flooring such as masonite below the floorboards to reflect sound. Acoustic foam underlays can also be laid under timber floors over concrete slabs to reduce sound transmission.
Similar principles apply to wall construction. The use of acoustic insulation is imperative when installing lightweight walls. If installed correctly, this type of insulation can allow a lightweight wall to function just as well as a masonry one, especially when combined with sound-rated plasterboard.
There are plenty of products available now that can help to solve existing noise problems, or to avoid issues in the future. Your choice will depend on the type and frequency of noise that you are seeking to control as well as aesthetic and structural considerations. In more complex situations the advice of an acoustic consultant can be invaluable.