Methods of noise control inside buildings

Optimal design of buildings includes noise control measures. Buildings designed for industry that involve noise producing machines require the most  careful planning. Architectural acoustics is the science of controlling sound within buildings. Noise suppression in the design of multi-unit dwellings and business premises that generate noise is also highly desirable, but often omitted because of extra costs. Increasingly, the best building codes require noise control.

People who buy a nice looking, expensive apartment or condo only to discover that they can hear their neighbors' noise above, below and on either side, all day and all night are at best disappointed. The architect is at fault for not considering their comfort and well-being. The builder is at fault for using cheaper, lower density materials in walls, ceilings and floors. Later additions of sound insulation and sound absorbing materials are usually less effective than properly constructing the building in the first place.

Noise inside buildings comes from the occupants and from mechanical systems such as elevators, plumbing, heating, ventilating and air conditioning units. Plumbing noises are considered in building codes that require noise damping water supply lines and drain pipes. Air flow ducts can be baffled to reduce noise.

Sound is propagated as pressure waves in the air and other materials. Sound can be transmitted through small air spaces such gaps between doors and frames. Sound is transmitted from air to materials that vibrate. Sound transmission is blocked by high density materials that do not vibrate. Sound insulation is achieved by high density materials that prevent the transmission of noise. Lead is the best material to block the transmission of sound.

Sound can be absorbed by porous materials which  convert sound energy into heat. Open cell foams and fiberglass are examples. Vibrations produced by machines can be reduced by damping mechanisms. Vibration isolators include springs and rubber mounts.

External Noise

People living in cities are exposed to noise at all hours of the day and night. Road noise is all pervasive. The opportunity to retreat to quiet home and work environments is a luxury. The best building codes require measurement of outside noise levels to determine proper building design. Architects can work with acoustical engineers with the goal quiet interior spaces with less than 45 dBA average sound levels. Denser exterior walls, double pane windows,  better roof materials, tight door frames and control of machine noises such as through wall air conditioners are required design elements.

The ABC strategy of noise control

A = Absorb 
B = Block
C = Cover-up (electronic sound masking)