In the same way that a speed camera or a red light camera aims to catch those who break the law, acoustic cameras do the same thing. In this case though, when exhaust noise triggers the camera, drivers can be penalized up to £100. A new report says that from June 2021 to February 2022, nearly 10,000 vehicles were caught emitting noise over the legal limit in the London Borough of Kensington and Chelsea in the UK.

Of those vehicles, the majority were BMWs, says a report from DrivingExperience. In second place were Lamborghinis, and the final spot in the top three was taken up by Mercedes-Benz. Ferrari, Audi, and Land Rover round out the top six in that order.

Acoustic cameras exist in many cities in the UK and newer cars are especially vulnerable to them. That’s because any vehicle built in 2016 or after that emits noise above 72 dB is at risk of triggering the camera. To put that into perspective, a Yale University source says that a normal conversation has a dB rating of between 60 and 70.

Read More: How BMW Is Eliminating Every Irritating Sound From Its i7 Electric Flagship

Older cars, built specifically between 2007 and 2016, must emit no more than 76 dB or about the sound of chamber music in a small auditorium. Of course, having a noisy exhaust can be the product of a great many factors. Perhaps there’s some sort of exhaust leak causing an increase in sound. DrivingExperience.com has an interesting way of phrasing another possible cause.

“Another reason for an ear-splitting exhaust is when the car’s engine becomes too powerful as a result of modifications,” it says. No word yet on what exactly constitutes “too powerful” but it also makes a good point that excessively loud sound can be damaging to one’s hearing.

“Long-term exposure to noise from road traffic in our neighborhoods and cities every day can cause hearing damage and heightened stress levels,” it says. Of course, city traffic can create 85 dB sounds so we’re not sure how many of the almost 10,000 trigger events that these acoustic cameras picked up were false positives.

In addition, there’s no specific language in the code about what happens when a car’s stereo sets off the acoustic camera. DrivingExperience.com doesn’t clarify how many of the events were triggered by noise other than a specific car’s exhaust. The UK also penalizes loud stereos in certain situations.