Posted By Booney Morning Tony, I'm no expert but, as I recall: when you are measuring, a long term average is required so integrating is done by the meter to 'average' the sound it is measuring - this is because sound can and does fluctuate a lot. Class 2 meters are slightly less accurate than class 1, usually due to the type of microphone the meter has. Also, most meter suppliers are happy to demo their products and of course, their reps are very knowledgeable and you can glean a lot of information from them. If you are going down the workplace noise route, I would recommend attending an approved course such as the Institute of Acoustics Certificate in Workplace Noise Assessment Hope this helps Kind Regards

Posted By Richie Hello Tony, In answer to your question, there are four types of Sound Level Meter, graded 0,1,2 & 3. The Type 0 integrating sound level meter is normally used in laboratories as a reference standard (for instance to calibrate other SLMs). Type 1 meters are rarely found as they would be used in laboratories and in the field where the acoustical environment can be closely specified / controlled, which is incredibly rare. Type 2 Integrated Meters are the type most commonly used in the workplace. These are very versatile instruments hence their popularity. Measurement of industrial noise, community noise and average SPL from a noisy product (or other sound source) are able to be undertaken using a type 2 Integrated SLM, it's key aspects being it's ability to average noise over a given period, along with it's ability to emulate the human ear by way of weighting the sound received (designated A-Weighting). There are other optional weightings commonly found on these instruments but the important functions are Linear and A-Weighted. Type 3 meters are used invariably for initial surveys, commonly fire & safety advisers carry these on their person to provide an indication of noise level, in the case of fire advisers this is really handy for ensuring minimum decibel levels, whilst in the case of safety advisers they are handy as an indicator when it is possible an in-depth survey is required. Hope this helps. Richie.

Posted By Adrian Watson I agree with the above; whilst it is often stated that a type 2 SLM is adequate, I don't know of any occupational hygienists who don't use a type 1 meter. A type 1 meter has an error of approximately 1 dB and a type 2 meter an error of approximately 2 dB. Regards Adrian Watson

Posted By Bill Parkinson Tony Would suggest you make contact with Castle Group and tell them what you are trying to measure and why. They will then tell you whether you can achieve this with either a class 1 or class 2 meter. They also speak plainly and you can hire the meters if required. Would also suggest that if you are not aware of differences between the classes then you need some training (which Castle do as well). By the way I do not work for them but have used a wide range of meters from a number of companies and they are good and easy to use. Regards Bill

Posted By Tony Gladman Thanks everyone who responded. TG