Noise Levels at Football Grounds
Thinking about the end of the football season here in the UK, my mind naturally wandered to the loudest football stadiums in the country. Naturally, we have a mix of supporters here at Moniteye, including Man Utd, Arsenal and Spurs, but with none of these clubs having ‘legendarily’ loud grounds, I decided to look into which grounds in the UK are officially the loudest.
My research first took me to Liverpool vs Chelsea and a Champions League Semi-Final game back in 2005, when a controversial Luis Garcia goal edged Rafael Benítez’s men into the final. Liverpool went on to become champions, beating AC Milan on penalties in the final, but the goal scored by Garcia has a record all of its own – this moment holds the record for the loudest noise level ever recorded in a football game in British history, a staggering level of 130 decibels.
The Liverpool Kop (Photo by Robert Cutts)
To give a little context to this noise level, there are a few things that this can be compared to, including a jet aircraft taking off 100 metres away, jackhammering and ambulance sirens. My favourite comparison, however, has to be a concert performed by The Who, held at The Valley in London, Charlton Athletic's ground, back in 1976. At 32 metres from the speakers, this concert clocked an amazing 126 dB and held the world record for the loudest recorded concert for the next eight years. This was subsequently surpassed by Motörhead, Iron Maiden, and finally Manowar who in 1994 hit an ear-splitting 129.5 dB. Since this event, however, worried that other bands would keep pursuing louder levels, the Guinness Book Of World Records retired the loudest band record and removed it from their books.
The Who in concert in Zürich, 1980 (Photo by Ueli Frey)
Back to The Who, Peter Townshend and Roger Daltrey have been left with severe hearing problems as a consequence of that legendary noise level. The Control of Noise at Work Regulations 2005 in the UK say that employers must take action to reduce noise exposure if it exceeds the lower action values of 80 dBA or 135 dBC, and the upper action values of 85 dBA or 137 dBC. Additionally, the threshold of hearing pain is around 120 dB, so how damaging could the 130 dB noise levels measured at Anfield have been to the crowds ears?
It is understood that any exposure to noise levels of 130 dB can be dangerous to hearing, even for a short time, and it is recommended to limit exposure to 130 dB noise levels to less than one second; essentially, there is no safe exposure time to 130 dB, and a single brief exposure can cause temporary or even permanent hearing damage.
Hearing aids may be a requirement following hearing damage
So, we have established that the Liverpool vs Chelsea game was exceptionally loud… or have we? Let’s for a moment ignore how sorry we feel for all of those now deaf Liverpool fans and have a look at what the reported noise level is actually telling us about the noise environment inside Anfield that night.
First, decibels are a logarithmic expression of two ratios, that is, one number compared to another. Without knowing what the second number in the ratio is, then the term decibel is meaningless… it might as well read 130 oranges, or 130 bicycles. It is often surprising to acoustic consultants how often no reference is given to a noise level measurement and we are forced to assume that we are talking about a Sound Pressure Level. SPL’s have a reference point of 20x10-6 Pascals or 20 μPa, which is approximately the lower limit of human hearing. For pedantries sake, let’s give the benefit of the doubt to the reported levels and assume that we are talking about Sound Pressure Levels.
A close-up shot of 130 oranges
Next, in order to understand the noisescape we need to consider the distance at which the measurements were taken. Were they taken on the centre circle? Or one metre from the crowd? If it was taken at one metre from the crowd, which would be an acousticians preference, which part of the crowd was it? Was it the Kop? Or was it an average of all of the crowd?
You will remember from example above that the sound level measured at The Who concert was taken 32 metres from the speakers. When discussing noise levels, it is important to define this distance as, at its simplest, noise levels are governed by the inverse square law. This law essentially states that, with every doubling of distance away from a source, the noise level will decrease by approximately 6 dB.
So, just for fun, let’s imagine we are at that concert and walking towards the speakers… at 16 metres away we are now in a noise level of 132 dB, and at 8 metres it would be 138 dB and so on. Of course, in practice this wouldn’t work quite like this as there would be an array of speakers, multiple reflections and absorptions from around the ground, and even the temperature inside the stadium will have an effect on the noise level. But this does demonstrate that knowing where a measurement is taken in relation to the noise source is vitally important.
A graphical representation of the inverse square law (image by Borb)
Finally, although there are more parts to this we could poke holes in, let’s consider one more factor; frequency weighting. No noises, with the exception of true tones, contain only a single frequency, and a crowd noise would likely have frequencies stretching across the human hearing range of approximately 20 Hz to 20,000 Hz.
When in acoustics we are discussing noise levels, we often weight the results, typically to approximate how the human ear will respond to that noise. The most common of these is A-Weighting which reduces the impacts of lower and higher frequencies which humans aren’t as good at hearing.
Then there is C-Weighting, which is not as commonly used, but is often used for peak measurements and measurements of some entertainments where bass frequencies might be an issue.
Finally, there is Z-Weighting, which is akin to a zero rating where no adjustments have been made to the data.
A, C, and Z frequency weightings
There are other weightings too, so this begs the question, were the measurements made at a single frequency? Probably not. Were the measurements A-Weighted? Possibly, but without being explicitly told, we have no way of knowing, and of course this makes a difference. We are back to comparing oranges to bicycles when looking at different noise levels.
The moral of the story is that, without the full information and a knowledgeable reader, noise levels simply stated as X dB are meaningless. When measuring noise levels for any application, it pays to have good records, the correct equipment, and most importantly, a qualified and experienced engineer carrying out the survey. Here at Moniteye, we are proud to have engineers who are members of the Institute of Acoustics, meaning that you can trust the expert services and advice we deliver. When we monitor your site noise levels you can rest assured that the devices have been installed to capture the data that matters to you and that we will always be on hand to help you interpret that data.
Monitoring noise outside a road construction site
It wouldn’t be fair to tease the loudest football stadiums in Britain without some figures, so just for fun, here are the figures we found… for what they are worth! These are the loudest figures we have been able to find for any given season, most of which must be credited to American Factman, AKA @FEBallegiance on X (Twitter). If we have missed your team, or you want to add to the data, please leave a comment below and we will update the league. Want us to come and measure the levels at your ground? Give us a call on 01572 770780 and we’ll see you on match day!
