There are two different properties of sound that must be considered when designing a building, whether it is a Concert Hall at one extreme or a Home Workshop at the other.
Sound reduction from inside to outside and from room to room is the first consideration of acoustical design. Windows, doors, walls, roofs and ceilings must be designed to minimise road traffic, trains and aircraft noise intrusion, or machinery noise emission. Air conditioning equipment noise emission is also a common problem between residential buildings. It is mass that stops noise. A double brick wall will reduce noise by 55 dBA while a sheet of 4 mm float glass will reduce noise by only 25 dBA. The effective selection of building materials has great potential for cost savings in new buildings. "Do it right and do it once" saves money and prevents frustrating re-construction to overcome noise problems between neighbours.
Sound absorption within rooms is frequently overlooked by both builders and architects. In many modern buildings it is difficult to communicate or understand what is said on TV due to high levels of reverberation. People shout to communicate above the TV or radio. Tempers become frayed and family problems may become exacerbated by poor acoustics. In the past high levels of reverberation inside rooms was overcome by carpets and suitable soft furniture. However, the current move towards hard ceramic tile or polished timber floors in lieu of wall-to-wall carpets is causing serious acoustical problems in both commercial and industrial buildings. Sound absorptive acoustic ceilings are becoming an important component of modern buildings.