Warranty

7-Year Warranty

We focus on customer care, providing great support, advice and assistance.

5 stars

Rated 5 Stars

Pulsar Instruments are highly recommended and trusted by our customers.

Fast Delivery

Free UK Shipping

Free next-day despatch on all orders placed before 12 pm.

Secure Checkout

Secure Payment

Pay for your goods via our secure payment server, with a Credit or Debit card.

50 years in business

50+ Years in Business

We’re recognised and trusted noise measurement experts – Since 1969.

Sound level meter – What is the difference between a Class 1 & Class 2?

Sound control advice

Sound level meter – What is the difference between a Class 1 & Class 2?

By: Admin


We often get asked what the difference between a Class 1 and Class 2 sound level meter is, and which one do I need? This is actually quite a difficult question to answer. But in simple terms:

  • A Class 1 sound level meter is generally seen as more accurate than a Class 2 meter; and,
  • A Class 1 sound level meter is able to measure sound over a wider frequency range than a Class 2 meter.

The technical difference

The Class of a noise level meter describes its accuracy as defined by the relevant international standards. Sound level meters are defined by International Standards such as IEC 61672-1:2013 (or BS EN61672-1:2003). These standards define a wide range of complex accuracy, performance and calibration criteria that instruments must meet to be fit for purpose. Within the Standard, there are two allowable levels of tolerance and these are known as Class 1 and Class 2. Class 1 is more accurate than Class 2.

These Class 1 and Class 2 tolerances are necessary as a way of dealing with variations in the instruments. The variations are caused by the different electronic components used inside the sound level meters and because of the way different meters have been designed and verified. Even the test equipment used to check the sound level meters during manufacture will introduce some variation.

The two levels of tolerance

A Class 1 sound level meter is often called a ‘precision’ grade meter and a Class 2 sound level meter is a ‘general grade’ meter because of their difference tolerance levels. 

At lower and upper extremities of the sound frequency range* tolerances are wider, and at higher frequencies, the tolerances are narrower. At the outer extremes of the frequency range, you can expect Class 1 meters to have narrower tolerances and therefore a more accurate response.

Performance criteria:
tolerance limits at reference frequencies
(for IEC61672-1:2013)
Class 1Class 2
Frequency of 16Hz+2.5dB, -4.5dB+5.5dB, – ∞dB
Frequency of 20Hz+/- 2.5dB+/- 3.5dB
Frequency of 1kHz+/- 1.1dB+/- 1.4dB
Frequency of 10kHz+2.6dB, -3.6dB+5.6dB, -∞dB
Frequency of 16kHz+3.5dB, -17dB+6.0dB, -∞dB

Class 1 sound level meters need to measure sound over a wider frequency than Class 2 meters and meet narrower tolerances for all performance criteria. Class 1 is therefore seen as being more accurate than Class 2. So we can say a Class 2 meter has wider tolerances and is therefore slightly less accurate, but for most applications, the difference is not noticeable and as Class 2 sound level meters are a lower-cost compared to Class 1, for most users a Class 2 meter still meets the standard, is accurate enough and is fit for purpose.

*The frequency of sound is measured in Hertz (Hz) which is defined as one cycle per second. The higher the frequency, the more high-pitched a sound is perceived. Visit our Acoustic Glossary for more information on noise measurement terminology. 

Sound level meter - difference between 1 & 2 meters

Which sound level meter do you need?

Which meter you need will depend on what you want to use the meter for (i.e. what noise you want to measure), what measurement regulations you need to meet, and whether your measurements will be used as legal evidence (e.g. if you want your measurements submitted as legal evidence then you may prefer to use a Class 1 meter for increased accuracy). The Pulsar Nova range of noise level meters has both Class 1 and Class 2 and each offers a range of features depending on what you want to measure.

At the simplest level:

Find your perfect noise measurement equipment


You might also like:

You can find out more about the international standards governing sound level meters like IEC 61672 here


Featured Products


Related news stories

Noise Assessment Kits for Safety Professionals
Noise Assessment Kits for Safety Professionals

21st Mar 2009

Pulsar Instruments are pleased to announce the introduction of their New Noise Assessment Kits for Safety Professionals that give the Health & Safety professional a custom-made solution for resolving their…

Read full story

No-nonsense solutions for noise at work measurements
No-nonsense solutions for noise at work measurements

25th Mar 2009

The Pulsar Assessor range This year Pulsar Instruments Plc celebrates 40 years in the noise instrumentation business. We continue to provide effective, common sense and easy to use solutions for…

Read full story

NEW Pulsar Acoustic Toolbox Software
NEW Pulsar Acoustic Toolbox Software

30th Mar 2009

Software supplied as standard with all Model 33 and Model 30 Real-Time Sound Level Meters Pulsar Instruments Plc have added to the already impressive capabilities of the Model 33 Real-Time…

Read full story