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Terms explained

EC Market surveillance

Describes activities carried out by public authorities to ensure products are compliant with harmonised European legislation, do not endanger health or safety and do not present any other risks.

Noise test code

A test method, usually given in a European or International Standard, which defines how to obtain values for the noise emission of a machine. The test code will define parameters such as the conditions under which the machine will operate during tests and noise measurement locations.

Peak sound pressure level (Lpk)

A measure of the maximum instantaneous sound pressure at a specified location.  Exposure to high peak sound levels can be associated with immediate damage to hearing. Declarations of machinery noise emissions require the C-weighted peak sound pressure level determined at a workstation or other location to be given if it exceeds 130 dB. Try to avoid machines with a quoted peak sound pressure level as this may avoid the need to manage the risks from high peak sound pressure levels. Where some machines have a peak sound pressure level quoted and others of the same type do not, challenge manufacturers who do not quote it to check they have not made a mistake.

SNR (Single Number Rating)

One measure of the performance of hearing protection quoted on the packaging – HSE publication L108.

Sound power level (SWL, Lw)

Sound power is a value for the total noise energy produced by a machine. The sound power is a property of the machine and is not affected by room acoustics or the presence of other machinery.

Sound pressure level (SPL or Lp)

Sound pressure level is a measure of noise level at a location. For workplace noise, the sound pressure level is measured at the machine operator’s ears. Sound pressure level should be given alongside information about where it was measured relative to the noise source, what the machine was doing, and where it was situated to make the information meaningful.

Sound pressure level is dependent on many factors, such as the noise emitted by machines in the area, the noise directivity and room acoustics properties. For these reasons a sound pressure level reported under test conditions is likely to differ from that in your factory. The operator is likely to be working under different conditions, which could include reflections from walls and noise from other machinery.

Noise emission

Noise discharged by machinery or equipment. Normally this is quoted as" Sound Power Level."

Harmonised standard

A European standard which supports "essential requirements" of a New Approach Directive of the EU, such as the Machinery Directive. If its reference is published in the Official Journal of the EU it gives presumption of conformity with the essential requirements of the relevant directive within its scope.

Update 2012-12-07