When noise from the outside is a distraction, the windows   are often to blame. Exterior walls will typically block at least   between 45 to 50 dB of sound, but even a very high quality   window might not even block 40 dB. When possible,   controlling noise at the source is usually the best solution.   Sometimes a barrier can be built around the noise source.   Other times, the noise source can be relocated.

General rules of thumb for controlling noise from the outside:

• Typically, the noise transfer will go through the weakest structural element, such as the door, window or ventilation duct.
• When applicable, it is best to control exterior noise at the source.
• The isolation provided by a door is only as good as the extent to which it is sealed. If air can get around or under the door, so can sound.
• The majority of exterior noise enters through the windows. Dual-pane windows with increased air space can improve isolation.
• If the noise cannot be reduced to a satisfactory level, consider trying to mask the annoying noise with a more pleasant noise such as a water feature.

Case Study

Location: Private residence

Area of concern: A neighbor’s pool motor created an annoying hum that could be heard in the master bedroom.

Additional information: In this case, the first thing to do is to check the weakest points, such as windows and doors. Windows can be replaced with upgraded varieties, or acoustical inserts can be added for further control. Originally, acoustic absorption was mistakenly added to the inside of the room. This actually made the problem worse. Although the noise level within the room decreased, the absorption did nothing to reduce the exterior noise.

Questions to ask client:

• Describe the problem.
• What is the noise source?
• Where does the noise seem to be coming from? Under the door? Through the window? Through the ceiling? Etc.?
• What changes have already been made?
• Ideally, what improvements would you like to see?
  

Client feedback:

• An annoying hum is heard in the master bedroom. It interrupts sleep and interferes with other activities such as watching television and reading.
• The noise is coming from the motor from the neighbor’s pool pump.
• The windows are upgraded and an acoustic sealant has been applied to the doors.
• Ideally, the noise would be inaudible, or at least not distracting.
  

Evaluation: In this situation, encapsulating the noise source was the best solution. Vibration dampening was also used to control the noise. This solution completely met the client's needs.

Additional comments: There are certain noises that are difficult to control at the source, such as traffic noise. In such cases, look to control the noise at the path by erecting a barrier, such as a wall. Vegetation provides little, if any, noise reduction. If air can pass through, so can sound.