What do electric cars sound like?
Some car manufacturers are looking for a sound that warns of the presence of silent electric vehicles to people with reduced vision. But how should something that doesn’t sound like anything sound?
One of the great advantages of electric cars is without a doubt their low level of noise, which soon will change the chaotic sound landscape of cities dominated by the rumbling of combustion engine cars. Yes, new cars will not only free us from pollution, but also noise pollution, mainly caused by the current surrounding traffic.
19% of Spaniards are exposed to sounds toxic to their health. A study led by the Public Health Agency of Ontario (Canada) contends that dementia—a syndrome that affects more than 47 million people throughout the world, which will increase to 135 million in 2050 according to the World Health Organisation—may be intensified as a result of noise from cars.
The utopia of a city free of noise is close, but electrical cars are so silent that they can even go unnoticed, especially for people with reduced vision. ONCE has already reported the possible risks that the blind may encounter.
“When travelling at a speed lower than 20 kilometres per hour, hybrid and electric cars emit practically no sound, but many visually disabled people depend on sound to know when they can cross a street without danger,” explains the Organisation for the Blind, which has requested a regulation for cars and bicycles, because the probability of a crash with a person “increases 40% compared to audible vehicles”.
The manufacturers are now delving into the fascinating world of acoustic design. They have the challenge of creating a sound for an object that doesn’t sound like anything. To give an example, how would a dog sound if we had to invent their bark?
For three years, the European Commission implemented a collaborative project intended to explore different solutions to make electric cars detectable with the prospect of introducing legislation similar to the one implemented by the National Administration of Traffic Safety in the United States, which requires all electric cars to emit some type of sound when they drive less than 20 kilometres per hour.
Some means of transport, like trams and buses, have a bell sound that alerts passengers and drivers, and several manufacturers already introduce the sounds when the car systems detect an object that is close that they might crash into.
These alarms only warn of danger when it is imminent. However, Don Norman, Director of the Design Lab at the University of San Diego, believes that the sound of a car should work like blinkers and brake lights: they communicate the movement of the car before it happens. “When we are in a complex environment, such as traffic in a city, the best thing a car can do is say: look, here I am”, explained the professor to the magazine Wired.
The solution proposed by the Ustwo design studio, which you can hear here was to change the tone and volume of the sound of cars as the proximity to danger increased, which served to warn about a possible collision in advance.
These acoustic signals are similar to those that were developed as part of a project sponsored by the European Commission (eVader), whose main work was based on the search for sounds that were capable of alerting users, on the one hand, and maintaining the noise levels under those of a combustion car so that the electric car continues to conserve one of its great virtues: silence.
However, another project carried out by the French National Research Agency called MetaSon concluded that this type of noise left out parameters that were important for people, like knowing if a car is accelerating or slowing down. For that reason, cars had to be equipped with their own sound.
Combustion cars produce sound naturally, but it needs to be invented for electric cars—a new sound that will remain forever linked to an object. A study carried out by the Institute for Research and Coordination in Acoustics/Music (IRCAM) in France confirmed that white noise, like buzzing, or noise similar to an engine or an exhaust pipe, is more acceptable to people than honking and bells.
But to create the sound of an electric car, the main challenge was to find a sound that people recognised. Naturally, they turned to science fiction, including films like Back to the Future II, THX 1138 and Gattaca, to see what type of sounds the creators had used for their futuristic cars. The IRCAM study concluded that, even if these sounds have proven to be believable by people, they are perhaps too dramatic for an everyday car.
The tests to find the sound that defines future cars are ongoing in their developmental phase. Until then, electric vehicles will continue not to sound like anything.