ENVIRONMENTAL NOISE ASESSMENTS
Sound Planning Limited has the knowledge, skills and equipment for a full range of Environmental Noise Assessments and written Noise Reports in accordance with the relevant British Standards.
Environmental noise surveys are required within a range of commercial and industrial projects in both the public and private sectors.
Sound Planning assist their client through the application process; liaising with the local authority, conducting the appropriate noise assessment, compiling the acoustic report, and providing a noise mitigation strategy, if required.
Local Authorities vary in the assessment criteria e.g. Westminster evaluate potential commercial noise nuisance against their ENV 7 environmental policy, and more particularly C46 - 50. Sound Planning will adopt the appropriate methodology depending on the local authority reponsible for the planning application.
BS4142: 1997 Noise Tests
BS4142 Noise assessments are normally requested by a Planning Officer or E.H.O (Environmental Health Officer) due to concerns of increased noise from proposed mechanical noise e.g. Fans, Air Conditioning Systems, Generators etc. applied for in a planning application to the local authority (Council).
Local Authorities can differ in their specific requirements and their interpretation of appropriate statutes, however background noise levels should be measured as broadband dB LA90, with the specific (mechanical/commercial) noise measured as an LAeq. It is usually accepted that a 10dB excess (specific noise over background noise) will create a situation where complaints are likely. When a report indicates that complaints are likely, Sound Planning will formulate an appropriate noise mitigation strategy and submit this with the acoustic report.
PPG 24 Noise Tests
PPG24 (Planning Policy Guidance 24) Noise assessments are normally requested by a Planning Officer/Local Authority due to concerns relating to construction of new residential dwellings (or change of use) in a high noise exposure area.
New dwellings can be exposed to road traffic, rail, air or mechanical/commercial noise which is unnacceptable
A 24 hour (longer my be required) noise test is conducted in order to determine the Noise Exposure Category (NEC) that the proposed property would fall into; this category would determine the level of noise mitigation measures e.g. glazing, ventilation etc. that would be required in order to provide satisfactory noise protection for the inhabitants.
NEC fall in to categories A, B, C or D.
Internal noise levels and appropriate building facade construction are detailed in BS8233: 1999.
Notes:
LA90 - The A-weighted sound pressure level of the noise at the assessment position which is exceeded for 90% of the given time interval; normally required for background noise levels.
LAeq - The equivalent continuous sound pressure level, a measure of the average sound pressure level during a designated period of time.
Please contact Sound Planning Limited with any questions you may have regarding the above areas of expertise.
Noise Level Meter Calibration:
BS 7580 - Specification for the verification of Sound Level Meters, specifies a limited but sufficient range of tests to verify the accuracy of the measurement instrumentation at various intervals. As a general requirement Sound Planning calibrates its noise meters before and after each noise assessment. The majority of the test procedures are carried out with an electrical signal substituted for the measurement microphone with a series of test signals being used to assess the performance of the sound level meter in respect of noise, linearity, frequency weightings, time weightings, peak response, RMS accuracy, time averaging, pulse range, sound exposure level and overload indication.
Many of the test signals used to assess performance are complex and are certainly not available to the majority of people involved on a day-to-day basis with the measurement of sound. The test for RMS accuracy for example requires that a reading obtained from a continuous 2kHz sinusoidal signal be compared with that obtained from a sequence of tone bursts consisting of 11 cycles of a 2kHz sine wave repeated 40 times a second and with an amplitude 6.6 dB higher than the continuous signal.