EST 1992





Compressed Air Systems UK

What Does Sound Power and Pressure Level Mean?

When you are researching the best air compressor to buy, the sound power level and sound pressure level are important. The question is, what do these phrases mean?

  • The sound power level tells you the total acoustic energy that a machine, or piece of equipment, radiates to its environment.
  • The sound pressure level is a measure for the effect of the energy of an acoustic source (or a collection of sources). It depends on the distance to the source(s) and acoustic properties of the surroundings of the source.

When you buy a new air compressor, you need to think about the sound pressure level that will be acceptable in your workplace. Some of the ratings sound complicated so we have tried to explain this in simpler terms in the table below. If you need any help deciding which compressor is best for you, just ask! You can ring our team on 0121 7533330, or contact us.

Common sounds and their decibel ratings

decibel ratings
Credit: Decibel Chart: All You Need to Know (
Nuair NB3800B/3M/100 Q TECH PRO UK (230 Volt) | 13.06 CFM Piston Air Compressor

We provide information on the sound power levels of our air compressors but it’s important to remember that the sound power level of a machine is a fixed value, where the sound pressure level always depends on position and environment. If you use your compressor in different conditions, the actual sound power might be different. If you need to keep noise to a minimum in your workplace, we recommend our range of silenced air compressors. We have large, small and healthcare-grade silent and low noise air compressors.

In relation to the EU Machinery Directive we speak about the “emission sound pressure level”. This represents the sound pressure level an operator or bystander is exposed to, in a free field above a reflecting plane.

Important – Air Compressors are measured and compared within the industry @ 4 meters. To comply with EEC regulations all air compressors have to be marked in LWA. This is a different measurement of sound which is taken from a different distance. For an example a typical 3hp piston compressor is rated at its lowest at 73 dB(A) @ 4 meters on the LWA scale this would equate to approximately 93 decibels. Please beware of this as all products have LWA marked on them with stickers similar to the image below.

decibel example

LpA, LwA

Levels are described in ISO standards, using the following abbreviations or descriptors:

Lp: sound pressure level, and LW: sound power level

If A-weighting has been applied, then the descriptors above contain the character A at the end, for example: LpA

dB and dB(A)

dB (abbreviation for decibel) is the “unit” for both pressure and power level. It’s not a unit because it’s the logarithm of a quotient, that’s why Lp and LW are both expressed in dB, each with a different reference. The decibel is essentially unit-less! The A in dB(A) is not supported by ISO standards. The reason is that the A must be contained in LpA or LWA, and with a proper description. That is what’s needed for a good specification, requirement or measurement result.

Safety Note: If you see db, DB or Db in relation to noise or sound levels you should not take the information at face value. It suggests that the author is unfamiliar with some important concepts. You should ask yourself if you can trust someone who does not know that dB must be used (e.g. knows were dB “comes from”) because it suggests that the person, institute or company lacks the most basic knowledge about sound levels and related subjects.

Sound power level


Theoretical average sound pressure level

LpA dB(A)

























Typical reduction




The decibel which is normally abbreviated dB(A) is the unit used to measure the intensity of a sound. The human ear is incredibly sensitive. A person’s ears can distinguish between wide ranging sounds. You can hear everything from brushing your fingers on a notepad to the loudest explosion or jet aircraft.

To put these differences into perspective a jet aircraft is 1,000,000,000,000 times louder than the quietest audible sound.

Looking on the decibel scale, the smallest audible sound which is near silence registers at 0 dB. An increase of 10 decibels equates to a 10 fold increase in noise to your ear.

Ready to Assist You

Whether you need assistance in making the initial choice, or you require ongoing support for your compressor, Compressed Air Systems UK is here to help. Our experienced team is ready to provide you with the information, products, and services you need to make an informed decision.

 Contact us

  • 24/7 Phone Support: Our experts are available around the clock at 01217533330 to answer your calls and provide immediate assistance.
  • Messaging Service: For detailed inquiries or if you prefer written communication, send us a message. We’re committed to responding promptly.
  • Live Chat: For quick questions or guidance, our live chat service is a convenient way to get the help you need.

We understand the critical nature of compressed air systems in your operations, which is why we strive to offer solutions that bring you the best in efficiency and reliability.

Visit Our Location: If you would like to see our range of products in person or speak to our experts face-to-face, our doors are open at Unit 15, Fortnum Close, Birmingham, B33 0LG. For directions or any pre-visit questions, give us a call at 01217533330.

With Compressed Air Systems UK, you gain more than just a supplier — you gain a partner committed to ensuring your compressed air systems are as energy-efficient and cost-effective as possible. Contact us today, and take the next step toward optimising your operations with confidence.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top
Call Now Button