Absorption

Absorption is used to reduce levels of reflected sound or sound created at a source.

What is absorption?

What is absorption used for?

Using sound absorbing materials in a working space reduces the resonance and the effects of reflected noise. Good sound absorbing materials are usually light, fluffy or porous, for example, polyurethane foam, fibreglass or carpet. But these materials are not good sound barriers, and they shouldn’t be used to create noise shields or barriers. However using a sound absorber with a sound barrier can be a very effective method of noise reduction.

Sound absorbing materials can be used to line cabs, mufflers, acoustic enclosures, walls, ceilings, engine compartments, guards and ducts to minimise noise levels.

When is absorption effective?

  • Absorption is more effective at reducing high frequency (high pitched) sounds than lower frequencies such as background noise, or the noise from an air conditioning unit. This is because of the length of the sound wave.
  • The thicker the material, the more effective sound absorption will be. Good sound absorbing materials you should consider using are:
    • acoustical ceiling tiles
    • acoustic foam  
    • acoustic fabric panels - these are usually a wooden frame, that has been wrapped in fabric with a layer of sound absorbing material such as fibreglass
    • certain types of fibreglass
    • elastometers (a flexible coating). Elastomeric materials are versatile because they are also effective at reducing vibration.
  • Changing different elements of a material can change the absorption qualities. For example, installing the fibreboard so it creates an air gap behind it makes it more effective as a sound absorbent material.
  • Regularly maintaining your sound absorbent material makes it more effective in reducing noise.

Choosing the right sound absorbent material

You need to understand the frequencies of sound your workers are exposed to, so you can choose the most effective material. A competent person with experience in assessing noise frequency and who understands the different types of absorbing materials available can help you identify the sound frequencies your noisy machine, equipment or process generates.

Once you know the characteristics of the noise, speak to an acoustic engineer to find out which sound absorbent material is the most effective for your workplace.