BS 4142 – Methods of Rating and Assessing Industrial and Commercial Sound

What is a British Standard (BS)?

British Standards are codes of practice and specifications that cover management and technical quality requirements. Standards give guidance and recommendations on dealing with managing a process, making a product, delivering a service, or supplying materials. The standards are voluntary, so are not bound by law and do not impose legal responsibilities. The British Standard Institution (BSI) creates the standards and currently has over 30,000 standards under their supervision.

BSI say that:
“Standards are knowledge. They are powerful tools that can help drive innovation and increase productivity. They can make organizations more successful and people’s everyday lives easier, safer and healthier.”

What is BS 4142?

BS4142 is a relevant standard regarding acoustics and noise control. The title of this standard is Methods of Rating and Assessing Industrial and Commercial Sound. In general terms, this standard outlines the impact of noise from sources such as factories or warehouses and the effect it has on those living around the noise source.

Carrying out an assessment surrounding BS4142 involves comparing the source noise to the background noise at a receiver (someone’s home) and the difference between the two levels.

The general conclusions that a BS4142 assessment reaches in terms of difference between background noise level and source level are:

  • Generally speaking, the higher the difference between the source level and the background level, the more significant the impact on those living around the noise source.
  • A difference of 10dB or higher presents an indication of significant adverse impact. This is not acceptable and needs to be addressed.
  • A difference of 5dB higher than the background level presents and indication of adverse impact. This should be avoided if it is possible to do so, but is less impactful than a 10dB+ difference.
  • If no difference between the background level at the receiver (0dB), then this is an indication of low impact and little to no adverse effect.
  • Alongside this, the standard takes into account the tone and characteristics of the sound, which to the human ear can make a sound more disturbing even at quieter levels. Characteristics include tonality, impulsivity, and intermittency. These characteristics are listed in BS_4142 and dBs are added to the source noise if it is deemed to have a distinguishing characteristic or tone. The addition of the characteristic is subjective and is often added to the source noise by an experienced acoustic consultant who is aware what to listen for.

Who uses this standard?

  • Environmental Health Officers
  • Acoustic/Noise consultants
  • Planning officials and design engineers
  • Anyone using the standard for planning/legal purposes.