‘Method for Rating industrial noise affecting mixed residential and industrial areas’

A standard used for assessing the noise impact of development in mixed use industrial/residential areas. Acoustic Associates (Peterborough) have used BS4142 to assess noise in many different situations since the standard was first introduced in 1996, most significantly when carrying out environmental noise assessments for residential or industrial development for construction related noise or when investigating noise complaints.

Acoustic Associates (Peterborough) also offer training courses in how to use BS 4142.

The standard describes a method for assessing whether the ‘specific noise’ from an industrial source is likely to give rise to complaints from residents of the adjacent dwellings. The ‘specific noise’ levels are determined outside dwellings. The specific noise level is determined for reference time periods of 1-hour for the daytime (7am to 11pm) and 5 minutes for the night time. Tonal or impulsive characteristics of a noise are likely to increase the scope for complaints and this is taken into account by adding +5 dB to the specific noise source level to obtain the ‘Rating Level’. BS 4142:1997 requires that the Rating Level of a noise is compared with the existing background noise (L_A90,T). Guidance given in the standard states that if the difference between the Rating Level and the background noise (L_A90,T) is +5 dB, it would be considered as being of ‘marginal significance’. This is usually taken as being an acceptable situation, as it is a reasonable compromise between the requirements of commerce and the amenity of residents. A difference of +10 dB indicates that complaints are likely. If the Rating Level is more than 10 dB below the background noise this is a positive indication that complaints are unlikely.