26th September 2023
The Magic of the Attenuator
Author: Wakefield Acoustics – Noise Control Specialists | Last Updated: September 2023
Whilst the humble sound attenuator may be a relatively simple product, it carries a degree of complexity in its design.
When addressing noise control problems, we often need to implement a combination of measures for acoustic enclosures and ventilation attenuators. To the layperson, it is quite easy to imagine how an acoustic enclosure or acoustic panel system works, in that this is a physical barrier blocking the line of sight and providing some mass between the source and receiver to reduce noise. However, when considering an acoustic splitter attenuator with open airways, the fact you can see the noise source from one end yet still achieve a high level of noise reduction can be difficult to comprehend.
An attenuator comprises of an outer casing, usually steel, though can be any opening for ventilation, (eg. concrete shaft/tunnel or builders work), with a number of ‘splitters’ or ‘baffles’ arranged symmetrically. These splitters are essentially individual casings filled with an acoustically absorbent media (eg. mineral fibre, fibreglass or acoustic foam), and usually with a perforated steel sheet to provide some resistance to impacts, whilst allowing a good open area to retain the acoustic properties of the retained materials. A typical attenuator will comprise multiple acoustic splitters and airways.
As sound waves pass along the length of the attenuator, they are absorbed into the acoustic insulation with the sound energy converted into tiny amounts of heat energy. The combination of the number and size of acoustic splitters and airways allows the acoustic performance of the attenuator to be varied to meet the required noise reduction.
When installing any item, including a splitter attenuator, into a duct or shaft used for airflow it increases the pressure in the system. This is particularly important when considering a retrofit solution, as any additional pressure will result in a corresponding reduction in airflow. Therefore, when selecting and designing attenuators it is just as important to design correctly for airflow as it is for acoustics.
With the number of factors involved, the design and selection of attenuators for ventilation systems can be a challenge to meet acoustic and aerodynamic parameters, whilst also checking that the physical size can be accommodated.
Should you have a requirement for the design and supply of industrial splitter attenuators or our other range of noise control products, please contact us.
Wakefield Acoustics has extensive experience in providing bespoke solutions for general industrial applications: