View from the top: The sound levels expert (Edward Crofton-Martin)27 August 2015
Not upsetting the neighbours with loud noise is now a priority for concert promoters and venue owners. Getting the right level is a matter of science, and, rather than being ‘noise police’, the practitioners of this art are often big music fans themselves
Who are you?
Edward Crofton-Martin, principal acoustic consultant at Able Acoustics. I am a Member of the Institute of Acoustics (MIOA), as well as an Accredited Associate of the Chartered Institute of Environmental Health (ACIEH) and an Incorporated Engineer (IEng).
What do you do?
I solve problems related to noise. More specifically, I specialise in acoustics and environmental noise control. This involves determining practical methods of noise control by applying the scientific theory of sound (acoustics). I work with events managements companies and promoters to help achieve a balance between music noise levels that are sufficiently high to make the event workable whilst at the same time minimising disturbance to nearby residents. Promoters and event managers are increasingly aware of the benefits of avoiding complaints and possible conflict with local authorities. I am also an accredited expert witness in the field of acoustics and noise control and have prepared reports and given evidence relating to entertainment noise in the High Court.
Where do you do it?
Most of my work is UK-based although I do get asked to provide advice and assistance for events outside the country. I have worked at Glastonbury, Hyde Park Concerts, Move Festival Manchester, Homelands Dance Festival and the Brit Awards, as well as at Earls Court with artists such as Muse, Kylie Minogue and Madonna. I also got to work at the former Millennium Dome while Sir Paul McCartney was using it as a rehearsal venue.
What do you do it with?
Sound pressure levels are measured in decibels, which work on a logarithmic scale. The actual measurements are done using specialised and calibrated laboratory grade equipment capable of measuring individual frequencies to get accurate and reliable measurement data.
When do you get called in?
It is generally a condition of the licence that a competent and experienced person is brought in at an early stage and we would start by liaising with all relevant parties, including promoters and the local authority. One of the first things that needs to be done is to check the viability of the event against recommended levels: a concert running below 95dB(A) does not tend to provide satisfactory entertainment for the audience while topography of the local environment may not be suitable if guideline limits are to be met. Should the proposed event location be viable we would then consider elements such as the timetable, running order, stage location, speaker layout/orientation and noise from set up and de-rig, sound checks/PA testing, vehicle movements and installation of welfare facilities. We would also identify the nearest noise-sensitive premises and agree suitable monitoring locations.
How do you set the requirements for each project?
This typically involves calculation. We use specialist software to build a computer noise model and assist in evaluating the effectiveness of any mitigation measures. This also helps formulate a noise management plan, which would contain measures to control noise, a complaints procedure and procedures in the event something goes wrong. Prior to the event itself we would undertake sound propagation tests. This is done using pink noise played through the PA system and then measured simultaneously at both the mixer and the nearest noise-sensitive premises to determine the maximum permissible levels. During the event we take measurements at the agreed locations. This allows us to assist the promoter in ensuring any set limits are not breached. Following the event we would report the measured levels as well as any investigate action that may have been required.
Are there different considerations for various types of gig?
Every event is considered individually but depending on the venue type and the amount of events to be held, the limits vary for music noise levels when measured or predicted to 1m from the façade of any noise sensitive premises. For events continuing or held between 23.00 and 9.00 the music noise should not be audible within noise-sensitive premises with windows open in a typical manner for ventilation. Control can be exercised in this situation by limiting the music noise so that it is just audible outside the noise sensitive premises.
What’s your biggest success to date?
Getting backstage passes to see my favourite bands and being paid for it.
What’s the biggest challenge in your work today?
Increasingly people seem prepared to resort to the courts to resolve their disputes. The expert witness work I do is always a challenge because the key is to communicate technical concepts in a manner the court can understand – and some of these and the applicable British Standards governing good practice are extremely involved.
What is the ‘issue’ that never seems to go away?
There is a popular misconception that over-estimates the use of foliage. That is the idea that if there are some bushes or hedgerows between the source and the receiver they are is going solve the problem by providing an acceptable amount of acoustic screening. Then there is always someone in the crowd who thinks you are the ‘noise police’ waiting to shut the event down, when the opposite is true.
This is #8 of 10 ‘views from the top’ appearing in PSNLive 2015, PSNEurope‘s 10th annual analysis of the European live sound industry. This year, we quizzed incumbents of key industry roles on the ups and downs of the business. The result is a range of insights (views from the top, no less) from a diverse group of individuals, all of whose careers are inextricably linked to the fabric of live sound.