Noise control is most effective if it can reduce noise at the source. We can prevent noise at its source by enforcing noise regulations and imposing tougher penalties. We should, for example, introduce penalties for faulty car and burglar alarms and establish noise control zones for cars and aircraft.
We should improve the design and construction of engines and other machinery and subsidise building materials with proven soundproofing properties.
Walls and ceilings are better at reducing sound if they have a space separating two layers, or if they have acoustic materials between them for absorbing the sound and reducing reflection. For example attach fibreboards to walls and ceilings with a 5 cm gap between the board and wall or ceiling.
Cover pumps, compressors and other machinery with 5 cm thick glass wool.
Plant vegetation such as trees along roads and around factories and other sources of noise. The denser the vegetation the greater the noise reduction. Reduction is approximately 10 dB for every 100 metres of trees. This is due to absorption by the foliage and scattering of the sound.
Reduce vibrations in machinery, pipework and other equipment, with sufficient support and regular maintenance. Tighten screws to reduce vibrations, replacing bearings, and parts that vibrate. Use vibration isolators and mounts on machines, pipes, ducts and electrical conduits. Isolators are as simple as pads of felt, cork or rubber or they can be made from synthetic materials that are more expensive but more effective. Reduce the speed of moving parts.
Control noise along the path of its transmission. Check doors and wall partitions. Most sound waves bounce around rooms and are reflected off walls and each reflection weakens the wave. Use of acoustic damping on walls and ceilings will help reduce the reflections, especially when placed close to the source of the sound.
We need to do more research, for example in creating better and cheaper materials for sound insulation and ways of making things run quieter.
Maximum noise levels exist in some countries. They are 45 dB near hospitals, 50 dB for suburban residents 55 dB for urban residents and 70 dB for industrial zones.