Architectural Solutions for Noise Control
Noise control practices for architectural acoustics include: inter-room noise transfer reduction, interior sound reverberation reduction, and exterior building skin augmentation. In the instance of construction of new (or remodeled) apartments, hotels, condominiums, and hospitals, many cities and states have strict building rules with acoustical analysis requirements for protecting building occupants. Considering exterior noise, the exterior acoustic environment needs to be measured for the codes for determining the performance standard needed for exterior building skin design. The architect works with the acoustical scientist for arriving at the best cost-effective means for creating a quiet interior (normally 45 dBA). For designing the building skin the elements of most importance are usually: glazing (double pane design, glass thickness, etc.), roof material, perforated metal (used internally or externally), caulking standards, exterior door design, chimney baffles, attic ventilation ports, mail slots, and mounting of through-the-wall air conditioners.
First Type of Interior Sound
Considering generation of sound within the building, transmission is of two principal types. Firstly, the travel of airborne sound through floor or walls and ceiling assemblies can be produced from either mechanical noise inside the building systems or human activities in close by living spaces. Human activities might include noise from amplified sound systems, voice, or animal noise. Mechanical systems are boilers, elevator systems, generators and trash compactors or refrigeration or air conditioning systems. Aerodynamic sources include pneumatics, fans, and combustion. Control of noise for aerodynamic sources includes pneumatic silencers, quiet air nozzles, and quiet fan technology. Because many mechanical sounds are naturally loud, the principal design element requires that the wall or ceiling assembly meets certain performance standards, which allows considerable reduction of the sound level reaching occupants.
Second Type of Interior Sound
Impact Insulation Class (IIC) transmission is the second type of interior sound. Airborne transmission does not cause this effect, instead from sound transmission through the building itself. The perception of IIC noise most common is from occupants’ footfall in living spaces on top. Noise of low frequency is easily transferred through the buildings and ground. It is more difficult to reduce noise of this type, isolating the floor assembly above must be considered or lower ceiling must be hanged on resilient channel.
Both of the transmission effects mentioned above may originate either from occupants of the building or from building mechanical systems such as plumbing systems or heating, elevators, ventilating and air conditioning units. In some instances just the best available quieting technology needs to be specified in the selection of such building hardware. In other instances for controlling vibration shock mounting of systems may be needed. For plumbing systems specific protocols are developed, particularly for water supply lines, for creating isolation clamping of pipes inside building walls. Considering central air systems, baffling any ducts that may transmit sound between different building areas is important.