Measuring noise patterns and noise pollution

Information on how aviation noise patterns and noise pollution are measured in the UK

Measuring noise patterns
It is comparatively straightforward to record sound levels in decibels (dB) at different points as an aircraft takes off – on the runway, at half a mile distance etc. The CAA has Sound Level Meters and Sound Level Analysers to do this; many airports, including Heathrow, Gatwick and Stansted, have their own equipment for the same purpose, in fact some airports are legally required to have such equipment.

This information is then correlated with details of the particular aircraft and its flight path using a Noise and Track Keeping (NTK) system. This allows close analysis of noise levels by aircraft type or by location, by altitude, by runway used, and even under specific weather conditions. In other words, the combination of precise sound level recording and information about the flight(s) that are operating near the recording point and at the recording time provides incredibly detailed insight into noise patterns.

Measuring noise pollution
To turn this noise information into a measure of noise pollution, we need to relate noise levels to the impact on people’s health and quality of life.

Some impacts can be measured objectively, such as the level of speech disturbance (i.e. how often noise means people have to raise their voices to be heard) or the level of hearing loss caused by loud noise. But most impacts are highly subjective. What is annoying, or disturbing, to one person may well not bother another. Though you can quantify these – perhaps through opinion polls or surveys – they are affected by a range of other factors, such as: 

  • what you’re doing at the time – noise will be a bigger issue if you’re trying to sleep than when you’re doing the vacuuming
  • who is affected – for example, people with young children may be more concerned about the impact on their children’s health, and
  • how accustomed you are to the noise.

To try and overcome this subjectivity, noise pollution is generally measured using two factors: 

  1. how loud the noise is – the maximum level recorded
  2. how frequent the noise is – is there just one loud noise on an occasional basis, or is there a near-constant level of noise?

Both factors directly affect the level of annoyance and impact of the noise. For some people, an occasional very loud noise will be highly disruptive; for others, the constant background noise will be more of a concern. 

More information about measuring the impact of occasional loud noise and continuous noise

Related Publications

Noise envelopes (2013)
Measurement and modelling of aircraft noise at low levels (2010)
Metrics for aircraft noise (2009)