Posted By tom field When measuring the dB(A)LEQ for the 8 hour period, would taking the reading for 120 seconds (this equates to 2 sixty second cycles of the affected machines)be sufficient to give a true reading of what operators are exposed to in a 8 hour period? Concerns are that only measuring the noise levels for 2 cycles, 120 seconds, may not be appropriate due to fairly uncommon happenings, i.e. the dropping of parts nearby. May a less common event, such as this, give a higher reading and possibly mask the most consistent source of the noise during the 8 hour period?

Posted By Ken Dickson Tom, 120 seconds may give you a representative figure to work with. Remember there are two reasons for taking the measurements. The first is to ensure you are not exposing employees to noise levels that could cause noise induced hearing loss, and the measurement you suggest may satisfy this. The second is for use in defence of any future civil claims for noise induced hearing loss. For this purpose, a 120 second sample would almost certainly not be considered to be as sufficient measurement to defend a claim. Also, would an extra few minutes be that much of a hardship? The choice is yours. Ken

Posted By Adrian Watson Tom, The most important question is - is the measurement representative? The only way that this can be answered is by knowledge of the shift. I once carried out sound pressure level measurements (with a type 1 meter) of a person using a degreasing bath; the sound pressure level was around 80 dBA - fifteen minutes later for one minute the operator poured the metal objects from a basket in the still. This produced an overall Leq of 96 dBA. This was the same as a noise dose measurement carried out on the person in an earlier survey that had been discounted as a spurious result! In conclusion you need full knowledge - use both a sound pressure meter and noise dose meters, with observations of the task to carry out a full survey. Regards Adrian Watson