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Acoustics Testing

Sound power


Claire Lomax
t: +44 (0)161 295 3030

Sound Power Level Measurement

The amount of noise a machine makes is a key consumer consideration when making purchasing decisions. It is therefore, beneficial for manufacturers to know how ‘noisy’ their products are in comparison to their competitors. In some cases it is a legal requirement to quote the Sound Power  Level  on energy labels, and on appliance and machine specifications.

The Sound Power Level is the acoustic energy radiated by a source. While the sound power level is fixed for any source, the sound pressure level will depend on the distance from the source and the acoustic characteristics of the room or environment it is located in.

At the University of Salford, we can undertake independent measurements of sound power level in laboratory conditions from very high to very low sound pressure levels (below 0 dB). Some of our sound power tests are UKAS accredited (UKAS accredited Testing Laboratory No. 1262). This information can be used  for marketing, and to support the research and development of quieter products.

We have measured the sound power level of sources like:

  • white goods (dishwashers, washing machines, ovens, fridges, fridge freezers, range hoods)  
  • vacuum cleaners  
  • office/IT equipment  
  • hand-held power tools  
  • medical equipment (for example oxygen concentrators, diabetic alarms and injection devices)  
  • sports equipment (for example motorised golf trolleys)  
  • shower pumps  
  • air-conditioning units  
  • emergency alarms sirens / smoke alarms  
  • military instruments (for example rifle sights, motors)  
  • lighting / LED units  
  • Audible warning devices (for example smoke alarms, carbon monoxide alarms and emergency vehicle sirens)  

Sound Power Level Standards

Our independent measurements conform to the major British Standard sound power methods which give general rules for measuring the sound power level that apply to all source type:-

BS EN ISO 3741:2010 Acoustics – Determination of sound power levels of noise sources using sound pressure – Precision methods for reverberation test rooms (ISO 3741: 2010)
BS EN ISO 3743-1: 2010 Acoustics – Determination of sound power levels of noise sources using sound pressure – Engineering methods for small movable sources in reverberant fields - Part 1: Comparison method for a hard-walled test room (ISO 3743-1: 2010)
BS EN ISO 3744:2010 Acoustics - Determination of sound power levels of noise sources using sound pressure – Engineering method in an essentially free field over a reflecting plane.

Details of our current UKAS Scope of Accreditation.
BSEN ISO 3745:2012 Acoustics – Determination of sound power levels of noise sources using sound pressure – Precision method for anechoic and hemi-anechoic rooms.

Sound Power Level/Airborne Noise: Test Codes

Some sources have test codes that specify mounting conditions specific to that type of appliance/machine. Test codes we work to include (please ask for codes not listed):

Vacuum Cleaners        

BS EN 60704-2-1: 2015        

Details of our current UKAS Scope of Accreditation.



BS EN 60704-2-3: 2002        

Washing machines and spin extractors        

BS EN 60704-2-4: 2012        

Tumble dryers        

BS EN 60704-2-6: 2012        

Fan Heaters        

BS EN 60704-2-2: 2010        


BS EN 60704-2-7: 1998        


BS EN 60704-2-9: 2003        

Electric cooking ranges, ovens, grills, microwave ovens        

BS EN 60704-2-10: 2011        

Range hoods        

BS EN 60704-2-13: 2017        

Refrigerators, frozen food storage cabinets and food freezers        

BS EN 60704-2-14:2013 +A11: 2015        

Shower pumps (liquid pumps and pump units)        

BS EN ISO 20361: 2015        

IT and telecommunications equipment        

BS EN ISO 7779: 2010        

Needle Free Injectors        

BS EN ISO 21649:2006        

Air conditioners, liquid chilling packages, heat pumps and dehumidifiers        

BS EN 12102: 2013        

Acoustic tests on childrens toys        

BS EN 71-1: 2011+A3 : 2014 [Acoustic Properties]        

IT and telecommunications equipment        

ECMA-74 13th Edition, June 2015        

Features of sound power tests at the University of Salford include:-

  • Fully equipped Laboratory including water supply and environmentally controlled conditions  
  • Measurements carried out in anechoic, hemi-anechoic or reverberation chambers  
  • All equipment fully traceable to National Standards  
  • Confidentiality guaranteed  
  • Professional reporting to cover all the requirements of each standard  
  • Technical expertise and independent advice on measurement requirements  
  • Excellent access to main transport routes with convenient loading and storage facilities  
  • Opportunity to witness tests if required