Noise control at path

ENVIRONMENTAL STUDIES
Lesson 18: Noise pollution

Noise control at path

If noise cannot be reduced to a desired level at the source, then it can be reduced in the path in between the source and the receiver by using the following techniques.

  1. Orientation of Location: By moving the source away from the noise sensitive area, the noise can be attenuated.
  2. Enclosure
    1. Housing the noisy machines in isolated buildings can reduce the noise.
    2. A glass cabin may be provided for the operator of a noisy machine.
    3. Thick walls and heavy materials are more effective. A 25 cm. Thick wall can attenuate noise level by 45db (A).
    4. Double walls separated by an air space can act as the most effective barrier. Wider the air space, lesser will be the noise transmission.
    5. An operator confirmed in a chamber lined with absorbent material will experience some 5-10 db (A) less sound than in an ordinary chamber.
  3. Silencers: These can be used to suppress the noise generated when air, gas or stream flow in pipes or ducts, or are emitted into the atmosphere.
  4. Pipe lagging: Screens and barriers: a masonry wall can be used as an alternative to enclosure and can achieve attenuations of 10-20 db (A). Their effectiveness reduces the increase in the distance of noise source from the screen.
  5. Acoustic screens and barriers: A masonry wall can form a substantial barrier. Such acoustic screens can reduce direct noise transmission by up to 15db (A). Their effectiveness reduces the increase in the distance of noise source from the screen.
  6. Absorption treatment: Where there is a high degree of reflection of sound waves, introduction of an acoustically absorbent material, in the form of wall treatment (wall first covered with a thick layer of mineral wool and then with a polythene sheet), will reduce noise level by up to 10db (A) and will not reduce the noise radiated directly by the source.
  7. Damping: When large panels are radiating noise, a significant reduction can be achieved by fitting damping pads.
  8. Green belt: Location of green belt around residential areas can act as noise barriers. They can reduce noise level by absorption by ground cover and tree foliage.
Index
Previous
Home
Last modified: Monday, 2 January 2012, 7:21 AM