Guide offers sound advice

An eight-point guide available from Cirrus Research offers advice on how to choose appropriate noise measurement tools and outlines some of the issues that need to be considered - even after equipment has been purchased

According to HSE statistics about 1.7 million workers are thought to be exposed to noise above levels considered safe. It is estimated that around 100,000 people have suffered hearing damage because of their work with between 21 and 36% of these in engineering occupations.* Employers are expected to measure the level of noise in the workplace so that appropriate preventative action or protective equipment can be introduced. Noise measurement equipment is needed to carry out this activity and with so many choices available, and with prices ranging from £20 to £5000, deciding which one to buy can be confusing - and expensive if the wrong choice is made.

To assist with the selection process, Cirrus Research has put together an eight-point plan:

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: The equivalent continuous A-weighted sound pressure level (LAeq); the maximum C-weighted peak sound pressure level (LCPeak). It is important to 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. A noise dosemeter offers a solution as it can be worn for the entire shift continually measuring the noise levels and no further calculations will be required.

Step 2 - Accessories included? Cirrus Research believes is advisable to buy a sound level meter or noise dosemeter as a complete kit. In general the kit will contain the instrument, a suitable acoustic calibrator, a windshield and a protective carrying case.

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.

Step 3 - Recalibration and servicing Noise measurement instruments are precision tools, and the level of accuracy required from them is high. Reputable manufacturers spend time and effort ensuring their instruments meet these standards and it is important to keep the equipment at the same 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; when recalibrated its performance should be checked against the original specifications and standards.

Step 4 - Meeting specifications? The latest sound level meter standard gives two levels of accuracy, Class1 and Class2.

The Control of Noise at Work Regulations 2005 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 - BS EN 61252:1997.

Step 5 - 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 sufficiently accurate measurement. An expensive instrument may provide the data required, but the training required could be expensive. Therefore, it is recommended to choose an instrument that meets your requirements while keeping it as simple as possible and the cost realistic.

Step 6 - Simple to use? Ensure the product you buy is user-friendly.

Ideally you need a product that enables you to see all 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 - on some equipment, even these fundamentals are unclear.

Step 7 - Make sure equipment is Futureproof Find out how your investment will be supported. A reputable manufacturer should: Regularly conduct research into noise measurement regulations and requirements to ensure they are kept up-to-date with changing needs; have an established R&D team that ensures your equipment contains the latest functionality; offer free software updates; provide upgrades so you can easily change the use of your equipment without having to invest in new hardware.

Step 8 - Supplied with software? Not all noise measurement equipment comes with reporting software as standard. 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 some providers charge a license fee and this can prove expensive.

*www.hse.gov.uk/pubns/eis26.pdf