As electric vehicles (EVs) become more common on our roads, new research from Chalmers University of Technology warns that current warning sounds may not be effective in complex environments—posing a risk to vulnerable road users.
The study examined how well pedestrians could locate acoustic vehicle alerting system (AVAS) signals from hybrid and electric vehicles, travelling at low speeds.
While these signals meet international detectability standards, researchers found them difficult to locate—especially when multiple EVs emitted similar tones simultaneously.
“In a real traffic environment there are usually many different types of sound,” explained Professor Wolfgang Kropp of Chalmers’ Department of Architecture and Civil Engineering. “The way the requirements are worded allows car manufacturers to design their own signature sounds.”
The experiments involved 52 participants tested in soundproofed chambers using speakers to simulate the AVAS signals of one, two or three EVs, plus a traditional internal combustion engine.
Background noise from a quiet carpark was also introduced.
Participants were asked to identify the direction of the sounds.
The most challenging scenario involved a two-tone EV signal emitted from three vehicles at once.
Not one participant successfully located all such signals within the ten-second limit.
In contrast, the sound of a combustion engine—characterised by familiar short, wide-frequency pulses—was much easier to detect.
“Naturally, as acousticians, we welcome the fact that electric cars are significantly quieter… but it’s important to find a balance,” said lead researcher Leon Müller.
The findings highlight a gap in safety standards: current regulations focus on detectability but not localisation.
As Müller noted, this becomes critical in environments such as supermarket carparks, where multiple EVs may be moving in different directions.
The team is now expanding its work to explore how AVAS signals impact people in real-life settings, aiming to develop sound cues that are both effective and unobtrusive.
