Noise NOT at work #2: How loud is…Historic Motorsport? A weekend at Spa Francorchamps by Johan Beavis-Berry (WBM)
In a world where road traffic noise is near-omnipresent, it might seem hard to believe that anyone could find pleasure in the sound of cars. In fact, motorsport enthusiasts would be delighted to explain the nuances of why a Porsche flat-six engine is without question the greatest sounding engine of all time, for example…
Despite harbouring highly subjective opinions on automotive sonic perfection, car fans will admit that racing events can be loud. Signs like the one below are plastered across UK motorsport venues, yet noise exposure is not always at the forefront of spectators’ minds.
As a conscientious acoustician and musician, I take my hearing seriously. My earplugs are always close at hand, and I’ll use them even in circumstances that wouldn’t raise the eyebrow of a librarian. Needless to say, dozens of unattenuated racing cars passing by at full speed would be unwelcome at a library.
The trip to Spa Francorchamps (in September 2025) began with a seamless drive from Gloucestershire to Folkestone and the Eurotunnel. The 3.5-hour backseat journey by Land Rover Freelander yielded an overall sound level of 74 dB LAeq,T with general conversation and no music – so far, so good. To preserve the battery of the dosemeter, no measurements were taken during the European leg of the journey, leaving opportunities for further research comparing British and French road noise. Similarly, typical sound levels in Belgian bars were undocumented on this occasion, with subjective impressions blurred by intoxication.
Friday morning saw us slightly worse for wear and arriving at the circuit by 10:30, with racing already underway. Once coffees had been obtained, we spent some time in the paddock area, where competitors were busy preparing their cars. I optimistically left my earplugs in my pocket but quickly changed my mind after observing levels of up to 110 dB(A) on the dosemeter. Our spectating began on the start/finish straight, with a combined race for pre 1965 and pre 1981 sports cars, though a long safety car period following a crash at La Source hairpin significantly lowered the noise exposure. To pass the time, we wandered through the Formula One pit area and found a Maserati 250F warming its engine. This led to the highest noise exposure of the entire weekend, with a whopping 143 dB LCpeak and sound pressure levels of over 116 dB(A) noted!
The afternoon was spent in the Raidillon grandstand, where a combination of tinny music and commentary through the PA system eliminated any chance of rest for the ears between races. The pre 1966 Grand Prix race was by far the loudest, with the pictured Maserati a clear winner for both best sounding and loudest car of the event.
The dosemeter only logs 1-minute LAeq data which masks the true drive-by sound level of the cars, but when the field was closely spaced, the dosemeter display registered sound pressure levels exceeding 110 dB(A). The overall measured sound level for this race was 95 dB LAeq,T, a full 10 dB higher than the following race.
Spectator histogram for Friday 26 September 2025 showing LAeq,1min and LCpeak values
Having enjoyed a full day of racing on Friday, we were content to spend more time infield on Saturday. The 6-hour race doesn’t commence until 4pm so we found ourselves in the paddock once again, where a Bugatti Type 35 warming its engine was no match for Friday’s Maserati. Even with our relaxed approach to spectating, we enjoyed a variety of races including Pre-War sports cars and an Alfa Romeo Cup which both yielded surprisingly modest noise exposure. Inevitably, we found ourselves in the bar, where rowdy voices, background music and distant racing yielded ambient sound levels of 80-85 dB(A). During this period, the chart for Saturday 27 September 2025 (overleaf) clearly shows a steady increase in ambient sound levels as spectators gathered for the big race.
Endurance racing pushes both car and driver to the limit and attracts only the hardiest spectators who are willing to sit outside until 10pm on a damp autumn evening. We passed the two hours until sunset on the pit mezzanine, experiencing drive by sound levels consistently above 120 dB LCpeak. A strategic leisurely dinner buffet halfway through the race had the potential to give our ears a break, though levels in the busy dining hall averaged 80 dB(A) which is too high for an effective rest area.
The night brings added intensity to the racing, with cars identifiable only by their headlights and exhaust note. To stave off the cold, we walked the length of the Kemmel Straight all the way to the semi-circular Bruxelles corner. Unsurprisingly, Kemmel gave our highest single minute of exposure of the day (103 dB LAeq,1min), where the fastest cars were comfortably exceeding 160mph as they passed by.
Spectator histogram for Saturday 27 September 2025 showing LAeq,1min and LCpeak values
In answer to the question ‘how loud is…historic motorsport’ an exhausting 12-hour day of motorsport resulted in an overall exposure of 87 dB LAeq,12hr. Our exposure on the day before was higher still, at 91 dB LAeq,8h.
To put this in context, guidance in the WHO “Environmental Noise Guidelines for the European Region” 2018 suggests that we should aim to reduce the yearly average from all leisure noise sources combined to 70 dB LAeq,24h. Converting the motorsport noise exposure over the weekend to a yearly average (assuming 365 days) equates to 62 dB LAeq,24h. Attending more than six weekends of historic motorsport in a year (without hearing protection) would cause this guideline level to be exceeded, based on the results of this investigation – and assuming no other elevated leisure activity noise exposure throughout the year.
In conclusion, regular attendees of historic motor racing events should remember to pack their hearing protection!
