There’s been a huge increase in the number of smart phone apps recently (1). In July 2015, Android users had 1.6 million apps to choose between, with users of Apple’s App Store close behind with 1.5 million.
All very interesting, but what’s this got to do with noise and football? Here we go, here we go, here we go.
A pilot study by NIOSH (National Institute for Occupational Safety and Health) noise researchers in 2014 (2) aimed to assess the functionality and accuracy of smartphone sound measurement apps to determine whether they can be relied on to conduct participatory noise monitoring studies in the workplace.
They found that certain noise apps for Apple smartphones and tablets may indeed be considered accurate and reliable, while Android and Windows developers did not offer apps that met the functionality needed for occupational noise assessments.
Similarly, a 2013 Canadian study (4) indicated that Android apps were inaccurate at determining noise levels and under-reported the true level of the noise. The IOS apps performed well at low intensity levels, but at 95 dB, measurements were inaccurate due to saturation (high levels under recorded).
Some apps tested in a 2014 study in the US (5) offered a calibration feature, but this wasn’t used in order to simulate how a typical (non-expert) user might operate the apps. Due to the inaccuracies of the apps as measured, no apps were recommended without calibration, and without complete understanding of the dynamic range over which the device can provide accurate measurements.
There is more, but the above is enough to get the picture. Some apps were ‘better’ than others, but there were issues with calibration and microphones and accuracy was questionable.
Sound level data from leisure industries is limited, although there is some information available on high sound levels from music, motor sport, etc. and some indoor swimming pool attendants are on the list of at-risk occupations.
But what about the football? Not much data has been published at the moment. Are you listening FIFA? (Maybe pre-occupied at the moment). I do have some spare weekends…
In the meantime, let’s look at what we do have to go on….
A few years ago, website Fan-charts set up a decibel meter (6) inside every Premier League club on three separate occasions during the 2010/11 season, taking an average to give a table of the top flight’s loudest supporters – ranging from 77-97 decibels.
Without being hypercritical (well OK, being a bit hypercritical), it is a fun article, but there are some things it would be useful to know to make sense of this. What sort of meter, was it calibrated, where was it placed, what is meant by average and what type of decibels do they mean? Unit B Dip students will no doubt have spotted all of this.
In 2014/15, the Press Association recorded decibel levels (7) at all Premier League grounds over two weekends, with each team playing both home and away. The scores of every club were combined to get a total and prove which fans were the loudest in the division. Figures varied from 152 – 167 decibels. (Er…? To put this into context, a jet plane taking off is roughly 165 decibels!) (7.1)
So what’s the problem with this study? Well firstly, why were the two figures added together? B Dip students will know that two identical noise sources have a total SPL of 3 greater than either source. So, twice 85 = 88. Try explaining that to the CEO or to the workforce.
Perhaps there’s some light at the end of this tunnel over in the USA… (sorry, mixed metaphor).
The loudest crowd roar at a sports stadium was 142.2 dbA, achieved by fans of the Kansas City Chiefs (USA), at Arrowhead Stadium in Kansas City, Missouri, USA, on 29 September 2014. (8) If this was dB(A) it was VERY LOUD. If it was dB(C) it was VERY LOUD.
However, a blogger revealed ‘Not only did KC fans cheat by having their cheerleaders scream into the mic 10 feet away but Chiefs didn’t make playoffs…..ahhhhhh too bad!! Century Link is still the loudest stadium in the world and the 12s are the loudest fans in the world!!!’ Fans will be fans.
Never been to a match at a stadium? This YouTube video shows footage of the twenty noisiest stadiums in the world (or so they claim!), have a watch to get an idea for yourself. There are no figures on the clip, but it’s a great watch! Maybe someone could get Lionel Messi to wear a dosimeter? (9)
My own research reveals the following. At a big game, an early home team goal was scored, LAFmax 114, LCpk128 (hand-held spot readings) were noted. A dosimeter (different time-based sampling settings) showed the same event to be around 104dB(A) & 128dB(C).
The crowd were excited and noisy, and the level in the home stand just before the goal was around 95dB(A). The same crowd, enthusiastically applauding a presentation a few minutes earlier just before kick-off, was measured over a short period at 95dB(A). Previously, I’d measured 97dB(A) and 123dB(C) over a short period in the away end at the same stadium.
At other points, crowd noise dropped to around 80dB(A) and fluctuated depending on the state of the game and the location of the meter.
Here’s an issue with both SLM (sound level meter) and app readings – how can we convert spot readings into something meaningful? With an integrating SLM or dosimeter, assuming a robust sampling strategy, the software will do the mathematics and then you can check against local law. Using the ever-changing figures dancing on the screen of a non-integrating meter (SLM or app) to work out an LAeq or LEpd over the duration of a football match or a day at work (both have varying SPLs at different times) is difficult.
At the moment, it appears that some noise apps could, with caution, be used to get a rough idea of some SPLs in a workplace. But I wouldn’t be off to convince any lawyers on this basis yet, m’lud.
And finally, the infamous vuvuzela at 127dB (10) (11). Wonder why it was banned?
Refs (pun intended)
- 7.1. http://www.decibelcar.com/articles/40-everything-else/87-dbequivalent.html