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How to select noise measurement equipment

23 January 2013

The importance of noise control in the working environment is becoming an increasingly recognised and widely discussed issue but selecting suitable noise measurement equipment can often be a daunting process. James Tingay

The importance of noise control in the working environment is becoming an increasingly recognised and widely discussed issue but selecting suitable noise measurement equipment can often be a daunting process. James Tingay offers some pointers

According to HSE statistics about 1.7 million workers are thought to be exposed to noise above levels considered safe and it is estimated that around 21,000 individuals who worked in 2009/2010 suffered hearing problems as a result of their occupation.

In an attempt to reduce this level of hearing damage, noise legislation designed to protect hearing and prevent noise nuisance is becoming tougher and more widespread. As a result of this the importance of noise control in the working environment is becoming an increasingly recognised and widely discussed issue and employers are expected to measure the level of noise in the workplace so that appropriate preventative action or protective equipment can be introduced.

But noise measurement equipment is needed to carry out this activity and with so many choices of equipment available and with prices ranging from twenty pounds to five thousand pounds, deciding which one to buy can be very confusing and expensive if the wrong choice is made. To simplify this process Cirrus Research has produced an eight point guide with advice on how to ensure you choose the best noise measurement tools for your application, and also outlines some of the issues that need to be considered even after the equipment has been purchased.

Step 1 Do the measurement functions comply with Standards, Regulations or Guidelines? The Control of Noise at Work Regulations 2005 requires the following measurements for compliance:

1. The equivalent continuous Aweighted sound pressure level (LAeq) 2. The maximum C-weighted peak sound pressure level (LCPeak) It is important that you have the right sound measurement equipment for the right situation. There are many situations where using a handheld sound level meter is not possible for both practical and safety reasons, such as employees with complex working patterns. This is where a noise dosemeter is the ideal measurement tool because they can be worn for the whole working shift continually measuring the noise levels and no further calculations will be required.

Step 2 Does the equipment come with all of the accessories required? It is always advisable to purchase a sound level meter or noise dosemeter as a complete kit and avoid combining units from different manufacturers. In general the kit will contain the instrument, a suitable acoustic calibrator, a windshield and a protective carrying case. One of the most important accessories is an acoustic calibrator. All noise measurement standards state that an instrument must be calibrated before and after each use and without an acoustic calibrator, this cannot be done and therefore any measurements made could be inaccurate.

The windshield will help protect the microphone from damage, even indoors.

Step 3 The importance of recalibration and servicing Noise measurement instruments are precision tools, and the level of accuracy required from them is very high.

Reputable manufacturers spend considerable time and effort to ensure their instruments meet these standards, therefore it is important to keep the equipment at the level of accuracy as when it was purchased. An instrument from a trusted manufacturer and meeting the latest standards should come with a calibration certificate and when recalibrated its performance should be checked against the original specifications and standards. To do this an acoustic calibrator cannot provide enough information about the instrument's performance as the microphone capsule needs to be removed. With many low cost instruments the microphone cannot be removed, therefore the recalibration should be carried out by the original manufacturer or by a qualified calibration laboratory.

Step 4 Does the equipment meet the specifications required? The performance of sound level meters, noise dosemeters and acoustic calibrators are set out in national, European and international standards. The latest sound level meter standard gives two levels of accuracy, Class1 and Class2. The Control of Noise at Work Regulations 2005, which are in force in the UK, states that with regard to sound level meters "Your sound level meter should meet at least Class 2 of BS EN 61672 - 1:2003. Personal noise dosemeters have their own standard with which they must comply, which is BS EN 61252:1997.

Step 5 Making sure the equipment comes with clear instructions The level of training and experience required to operate complex sound level meters can often get in the way of making good quality noise measurements.

However, a simple instrument that may require less training to operate, might not give enough accurate measurement. An expensive instrument may provide the data required, however the level of training needed could be expensive too.

Therefore, it is recommended to choose an instrument that meets your practical requirements whilst keeping the instrument as simple as possible and the cost realistic.

Step 6 Make sure the equipment is simple to use, straight out of the box Ensure the product you buy is userfriendly.

Ideally you need a product that enables you to see all of the relevant, important information in one place quickly, making it easier for you to report on your measurements. At the very least "on" and "off" buttons should be obvious - it is concerning to note that on some equipment, even these fundamentals are unclear.

Step 7 Make sure the equipment is "Futureproof" When you are looking at different manufacturers, ask some questions and find out about how your investment will be supported. A reputable manufacturer should: 1. Regularly conduct research into noise measurement regulations and requirements to ensure they are kept constantly up-to-date with changing needs 2. Have an established Research and Development team that ensures your equipment contains the latest functionality to meet all of your requirements 3. Offer you free software updates so you can continue to reap the benefits of your equipment investment for years to come 4. Provide equipment upgrades so you can easily change the use of your equipment without having to reinvest in brand new hardware Step 8 Does the equipment come with all the software you need to get the best out of it? Most noise measurement equipment doesn't come with reporting software as standard. You may only get basic downloading software supplied with the instrument so check what's included.

Putting together a report using your findings can be time consuming so it is advisable to ensure that the equipment is supplied with full reporting software for free as many providers charge a license fee and this can prove very expensive.

For more information or to acquire the full eight point guide please contact Cirrus Research on the number below.

James Tingay is group marketing manager at Cirrus Research.