New AI detection technology means that vehicles breaking legal noise limits can be detected, identified and the driver fined. We take a look at how technology from Intertraffic Award winner SoundVue and other systems like it work – and see how they are beginning to be deployed around the world in a new frontier for enforcement.
Modified exhausts, overrevved engines, pops, bangs and tyre screeches: all signs of anti-social driving and the excessive noise associated with it. Common complaints for the city dweller, but also increasingly for the residents of normally quiet villages and towns. Now there is a potential solution as ‘noise cameras’, the sonic equivalent of speed cameras, are being deployed in the US and Europe
Several big name ITS suppliers are now beginning to offer noise camera technology, but there are also some start-ups in this field, including one based in the UK that is having notable success. Intelligent Instruments was only established in 2019 but is already gaining an international profile with its SoundVue noise camera system, with deployments to Kensington and Chelsea Council in London, Manhattan in New York and the City of Knoxville, Tennessee.
“This technology is used to detect excess sound from nuisance vehicles. So, road vehicles, motorcycles and cars, which may have modified exhausts, or any car really that may be driven aggressively with excess revving,” says Reuben Peckham, co-founder of Intelligent Instruments.
Several design challenges emerged in the course of development. The question was not only how to determine with high accuracy if legal sound levels have been breached, but which vehicle in a small area is the source of the offending sound, and what kind of sound is being produced.
“It’s a precision noise monitor. So, it measures sound levels very accurately, when combined with three cameras and microphone array. It records video and audio until it triggers. It uses algorithms that trigger on exhaust noise, music and horns,” says Reuben.
The microphones are Class 1 accuracy (European IEC 61672-1 Standard rather than the USA’s ANSI), which is the highest precision available outside of a laboratory. This is an important feature because only a Class 1 recording is fully reliable as evidence in court. Currently in on-street applications the algorithm does not trigger for loud music (although that capability has been developed).
“The microphone array also detects the offending vehicle. So if there’s multiple vehicles in the video, then the microphone array is able to determine which is the vehicle that has caused the extra sound,” says Reuben.
This is known as passive acoustic location and relies on four small microphones set in a dish. Small differences in the timing of the sound are used to determine the position of the sound source.
“And that in turn enables the camera system to read the registration plate of the offending vehicle and that’s captured as well,” says Reuben. This relies on a straightforward ANPR system, comparable to that used in speed cameras and some tolling applications.
There is a patchwork of laws in different countries governing noise exposure at work, but it is generally agreed, via bodies such as the World Health Organization (WHO), that no one should be exposed to noise above 85dB, even in an industrial setting, during their working day. This is roughly equivalent to what a person would hear while pushing a petrol engine lawnmower. Recommended levels for other settings are lower. The WHO’s Environmental Noise Guidelines state that traffic noise in Europe should not exceed 53dB in the daytime and 45dB at night. In general night-time noise should be below 40dB.
Human factors
In the UK, ‘boy racers’ – a term for nuisance drivers – face public disapproval. Polls conducted by RAC put support for noise cameras at 58% and opposition at 22%. It is estimated that more than 18% of the UK’s urban population is exposed to harmful levels of noise.
The Kensington and Chelsea noise camera trial was well received, and the borough now boasts a total of eight cameras issuing £100 (US$126) fines. Trials in Bradford, Bristol, Great Yarmouth and Birmingham are underway. However, the system remains under effective human control. Unlike a speed camera, it is not automatic, and the final decision to issue a fine for breached noise ordinances must be made by an enforcement officer, who is asked to discern between anti-social driving and legitimate breaches of the limit.
“When the system triggers it records a clip, uploads it to the cloud, and enables the user to look at the data remotely through a web interface. So, they can look at the video, they can hear the audio, they can look at the noise level,” says Reuben.
Part of the reason for keeping humans involved in the decision-making process is that sometimes there is a perfectly good reason for a loud noise, and determining whether this is the case is a very subjective process, not suited to automation. Vehicle noise created at a vintage car event, for example, might be perceived very differently from similar noise on a normal day.
“Noise could be a Harley Davidson motorbike for you, but not for me,” says Dr Antonio Torija-Martinez, associate professor of acoustic engineering at Salford University. “And that’s both the beauty and the complication of it. Two subjects might be exposed to the same sound level expressed in decibels, but there are other factors influencing perception. That could be acoustic factors such as temporal characteristics, the frequency, and where the source is located; but also non-acoustic factors such as the importance and value of the sound of noise for us.”
Flexibility and human oversight are therefore important. While ordinances are couched in terms of a breaching a certain decibel level, not every loud sound is considered noise, and there are legitimate reasons to exceed sound limits such as sounding a horn to avoid a crash.
Health impacts
“A passing car that’s revving or popping and banging, particularly at night can cause sleep disturbance. And that’s probably obvious. But what’s slightly less obvious is the health effects from that,” says Reuben.
The WHO has identified noise pollution as the second most harmful environmental cause of ill health; only fine particulate air pollution has greater impact. The EU is actively working to bring down noise levels as part of the European Green Deal, with the goal of reducing the share of people “chronically disturbed by transport noise” by 30% before 2030. However, initial reports suggest they may fall short of this target.
“We have studies connecting noise with physiological effects such as heart diseases and sleep disturbance. We have quite a lot of solid, robust evidence quantifying health effects due to a noisy environments,” says Dr Torija-Martinez.
The WHO has calculated that there are at least 1 million premature deaths due to long term environmental noise exposure per year in Western Europe alone.
The experience of unwanted noise is one that everyone can relate to. The difference between life in a peaceful and quiet neighbourhood, compared to one that is plagued with unwanted sound is clear.
“So again there’s evidence that in terms of quality of life noise could modify your pattern of activities. For example, it might be the case that in summertime you don’t want to spend time in your garden, because of aircraft flying over you, or you have a railway line nearby; and these noisy events could also affect our sleep creating disturbance,” says Dr Torija-Martinez.
Reuben Peckham explains that to him it’s not just about law enforcement, but about bringing the tangible benefits of peace and quiet to residents. “It’s there to improve the lives of residents living in areas in which this is a problem,” he says.
This article first appeared in Intertraffic World 2024
Photographs: AdobeStock
