What’s all the noise about metrics?

By ICCAN Commissioner and acoustician Simon Kahn 

The language of acoustics is incredibly complex. How do you explain the impact of noise succinctly and accurately so that people understand who is affected and what impact it might have on them?  

Over the years, a wide range of noise metrics have been developed to try to help describe noise exposure from aircraft and the annoyance it causes more accuratelyBecause a range of different variants are usedtwo apparently similar numbers may be quite different so a background knowledge is needed to work out exactly what each metric means when applied to everyday life. 

While some airports have attempted to make noise outputs clearer, in most cases they are still quite hard to decipher, which can result in communities feeling confused and frustrated.  

There are national and international standards for noise metrics and measurements but there isn’t a magic metric which will fully describe noise and all its facets simply; but the way noise is measured, analysed and communicated to the public can be improved and de-mystified.  

That is the key message from ICCAN’s latest publication A review of aviation noise metrics and measurements. 

By reviewing the way noise is currently monitored, measured and reported by airports, and recommending how it can be improved and made more consistent and transparent, we want to help increase the level of trust between airports and their communities around noise management.  

We know there is a wealth of aviation noise data from different airports collected in good faith, but unless that is translated into something that people understand, it’s not much use.  

In the report, we recommend that the current L A e q-based metrics used for noise monitoring should continue. However, to better reflect the experiences of those people on the ground, we are also proposing that supplementary information, such as Single Event metrics, are included alongside the L A e q based metric, to create a fuller picture So, in practice, this could include communicating the number of planes due over a flightpath during a specific timeframe, as this would pre-warn people of the number of flights to expect as well as the overall average noise and present a more realistic experience. 

The report also recommends making more noise data available online, improving the presentation and explanation around it, and making more temporary noise monitoring available to local communities so they can see the noise levels in their local area and understand the impacts.   

Over the coming months we will begin work developing best practice on how noise data transparency can improve, how airports provide noise monitoring for local communities as well as developing some guidance on the approach, standards and quantity of aviation noise recording and monitoring. 

Metrics is a key issue and one that many people have spoken to us about, so we hope our work leads to greater trust and transparency between airports and their local communities.   

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The Independent Commission on Civil Aviation noise ceased operating on 30 September 2021.

You can read the Government’s statement on ICCAN’s closure and Head Commissioner Rob Light’s letter to the Minister to learn more.

Any further questions about ICCAN’s work or aviation noise should be directed to the Department for Transport.