Permitted Noise Levels
Contrary to popular belief there is no decibel limit that needs to be exceeded for noise to be categorised as a ‘statutory nuisance’. Investigating officers will sometimes use sound level meters to help them assess nuisance but for most cases this sort of evidence is unnecessary and they will rely upon their experience and opinion. There are so many variables involved with noise disturbance issues that prevent a general acoustic limit being set.
The Noise Act
Separate legal provisions relating to night-time noise provide powers to local authorities that enable officers to issue fixed penalty notices where noise exceeds a specified decibel limit. The procedure involves a warning notice first and applies between the hours of 11pm and 7am. Due to a number of difficulties in its application the ‘night-time noise’ provision is rarely used in practice though. In addition, because of limited local authority resources, many local authorities may not provide a night time response service by which to enforce the provisions.
In Scotland permitted decibel limits also apply to the daytime and evening hours (where the local authority have chosen to adopt the provisions).
Guideline Noise Levels
Different acoustic indicators are more or less suitable for the assessment of different types of sound. Most are chosen for the need quick and easy application. Outside the legislation there are a few commonly used guides that are applied in order to get a better understanding of noise. They are not legally binding limits though. Examples include:
The Pop Code – Well out of date now but a couple of the noise levels specified in the code are often transposed to premises licences involving live music and outdoor concerts.
British Standard (BS) 4142 – Recently updated, this provides a method for rating industrial and commercial noise. Often used in planning processes and to assess constant noise sources.
WHO Guidelines for Community Noise – Again, these are very old now. They provide some guideline values for background noise experienced in a residential setting.