SCOTS scientists have finally answered a question that has troubled mankind for decades: What is the ideal volume for an outdoor rock concert?
The team from Napier University, Edinburgh, wanted to find a sound level which was high enough for most fans without annoying too many neighbours.
And they have discovered that 97 decibels – about the same as standing next to an electric lawnmower – is pitch-perfect.
At that volume, about 80% of fans will be happy and only 20% of nearby residents will be irritated.
Whacking up the PA system to 101 decibels – equivalent to standing next to a pneumatic drill – is likely to double the number of disgruntled neighbours.
Of course, rock stars are not supposed to care about unhappy residents or their own hearing, but the UK Department of the Environment is concerned about the issue.
There are an estimated 650 outdoor concerts in Britain every year and sound systems are more powerful than ever.
Current limits range from 100db in stadiums to 90db for small clubs and 85db for urban parks.
The way the decibel scale works means small numerical differences are significant. Sound energy doubles for every three decibel increase.
But Richard Mackenzie, the director of Napier University’s building performance centre, said the urban park limit was too low for many concert-goers.
He said: The limits…were very much based on experience of local authorities and promoters rather than objective research of audience and householders’ opinions.”
Mr Mackenzie’s team interviewed hundreds of residents and concert-goers following major outdoor gigs.
Some 38% of residents were annoyed when the volume went above 100db but that figure fell to just 17% if the noise level was pegged at 97db.
One of the concerts studied was Pink’s performance at Hampden, Glasgow, in 2010. Relatively low noise levels meant only 18% of neighbours were annoyed.
Kiss, however, annoyed 45% of people living near Wembley Stadium in London the same year when their noise levels soared.
Ironically, the study found that the hard-of-hearing and those with double glazing are the most likely to complain. The first group are more susceptible to low-frequency noise while the second tend to be irritated because they can still hear the music.
The Chartered Institute of Public Health will use the research to issue new guidance to local authorities.
Concert promoters said they hoped the findings would increase the number of outdoor concerts given permission to go ahead.