BS 4142

In order to carry out a BS 4142 assessment, the practitioner must establish the typical background noise level (at the time(s) the source being assessed operates/will operate), the specific noise level (from the source) and the ambient noise level (source plus residual noise). 

The (likely) character of the noise source being assessed must also be evaluated at receptor positions.

The sound level meter(s) must be BS EN 61672 Class 1 and the sound calibrator(s) must be BS EN 60942 Class 1. 

The standard also advises that, where appropriate, instruments for measuring meteorological parameters should be deployed during long-term unattended measurements. 

ANV Measurement Systems sell and hire instrumentation which satisfies the requirements of BS 4142 and which can help to carry out the assessment robustly and relatively easily.

The extremely low power consumption of the Rion NL-53 (and 52 previously) and full Class 1 performance with or without weather protection for the microphone, together with ANV’s outdoor kit, is an excellent and widely-used combination for conducting long-term unattended noise surveys. The meters can be provided with octave/third octave options and a really practical wav file recording option which enables audio to be recorded all the time, some of the time or to be triggered by level (with different trigger levels possible for four time periods).

The NL-53 is able to measure and store comprehensive data including the simultaneous measurement of processed (e.g. 15 minute Leq, Lmax, Ln etc) and short-sampled data (eg 10 or 100 msec Lp). 

The combination of a Rion logging sound level meter, ANV’s outdoor kit and Rion outdoor microphone protection has become the accepted means of establishing baseline noise levels for windfarms. 

The Norsonic Nor145 is able to simultaneously measure noise levels with two time profiles (A and B) within the overall Global and Profile Time period for each measurement. Octave/third octaves and audio recording are also available for the Norsonic Nor145. It is possible, for example, to carry out 1 hour and 15 minute measurements simultaneously. If you have both the octave/third octave and FFT options for the Nor145, the FFT and octave/third octave levels can be measured and viewed simultaneously. 

If the noise source being assessed is operational both the Rion NL-53 and Norsonic Nor145 can record audio files and short sample Lp data to enable objective analysis of the tonality and impulsivity of the sound when measured at the receptor position(s). Both meters can be equipped with an FFT option which supports some degree of analysis of tonality on site. Both meters, when equipped with third octaves, can of course be used to directly apply the flawed “objective” third octave method for tonality on site. 

Application of the reference method for tonality and impulsivity requires pot-processing of the the instruments’ wav files, using Rion AS-70 for the Rion NL-53 or Norsonic Nor1026 NorReview (with the appropriate options) for the Norsonic 145.

ANV Measurement Systems sell and hire these systems and also supply professional weather stations to monitor weather conditions during BS4142 surveys. 

If you are not sure of the best equipment for your BS 4142 assessment call us. Our experts in sound and vibration are available during normal UK office hours. 

ANV Measurement Systems UKAS Laboratory (0653), with it’s standard 5 day turnround, calibrates all major manufacturers’ instrumentation.