Electric cars

Street noises: a battery-powered symphony for electric cars

In their basic form, electric cars are quiet. Hans Zimmer wants to change that.

The Oscar-winning composer behind Gladiator and The black Knight goes from the big screen to the road to answer a question the industry has been asking for years: what should an electric car look like?

For a century, the unmistakable hum of beating pistons has sounded in vehicles, from the smallest sedan to the loudest racing car. A battery-operated world erases the soundscape.

“It’s a chance to end the dictatorship of the internal combustion engine,” Zimmer said.

“We have the opportunity to sonically return to a pre-industrial revolution type environment [before the combustion engine]then to something completely new.

It is working with BMW to develop a series of audio cues, ranging from noises when a car starts to the rising pitch when it accelerates, for use in its electric models.

This year, the sounds created by Zimmer and a team from BMW will be present in two new models, the iX and i4 electric cars.

Dedicated audio teams working at automakers in Detroit, Japan are tackling the same issue. Perhaps unsurprisingly, the answer to how an electric car should sound varies wildly.

Porsche, a brand intrinsically linked to the purr of engines, tried to diffuse artificial noises in the cabin of its Taycan, Jaguar used a digital growl in its electric I-Pace, while the first Nissan Leaf cars emitted a hiss ” extraterrestrial”. ring.

But for its new range of battery-powered models, Nissan surveyed drivers and found most just wanted silence.

“They really appreciate the quiet driving experience,” said Paul Speed-Andrews, who leads the company’s audio team in Europe. “People universally want the thing to be quiet.”

Paul Speed-Andrews, who worked at Nissan’s European Technical Center for 16 years, is a noise and vibration expert

BMW Sound Creative Director Renzo Vitale stands next to a vehicle

Renzo Vitale, BMW’s creative director of sound, says the right sound can help make electric vehicles safer

“It’s fair to say that the majority of our customers view our vehicles as a functional object, not a sports car,” he added.

BMW, on the other hand, says it wants to use sound to make drivers feel more connected to their electric vehicle and improve the driving experience.

The acceleration noise Zimmer created was inspired by the Shepard Tone, an auditory illusion of a constantly rising pitch he used to create tension in his score for the film Dunkirk. With the car set to the “dynamic” sports mode, it also includes a note that starts in a low register and continues to drop as the pace picks up.

But the risk is that racing impulses lead to faster driving.

“The thrill of driving should be fabulous, but we would also like to achieve a safer driving experience,” Zimmer said. The right sound can help make vehicles safer, he added.

“If you think about it, it’s so obvious to me that we think the eyes looking ahead of the road are the primary means of maintaining safety, but it’s really our ears that have full surround sound where we gather information about our security.

“Sound determines our emotion, so we can use it to help make [the cars safer].”

When creating the sounds of an electric car, composers are torn between reproducing engine sounds and experimenting with new options.

The Volkswagen team tried orchestral and electronic sounds, and settled on the latter, said Indra-Lena Kögler, one of the project’s sound engineers. Even so, they were mindful not to put off potential customers with irritating noises.

“If someone is in love with the shape and you come in with a weird sound, the customer might say it’s not me, I’m leaving,” said Klaus Bischoff, head of design at VW.

Nissan ultimately decided that the sound of its electric cars should be “somewhere close to a gasoline engine”.

“Anything we generate should be considered authentic sound associated with a vehicle, it cannot be bird chirping,” Speed-Andrews said.

BMW opted for a mix of traditional instruments and synthesized sounds, with female choral voices used when the vehicle starts and acoustic horns and strings for the more relaxed “expressive” driving mode.

“When we mentioned this at BMW development meetings, no one believed this approach could make sense,” said Renzo Vitale, creative sound director at BMW who worked with Zimmer on the audio project.

“But the first time the council [members] sat in the car and drove, they came back and said “I felt like a songwriter driving the car”.

The exterior sound of the vehicle is also very important, to comply with pedestrian safety rules.

One option used by Nissan is two tones, one higher at 2,500 hertz to cut out other sounds, the other at a lower frequency of 800 hertz which tends to be easier for older people to hear.

“It avoids anything around 1,000 hertz, where most of the noise is,” Speed-Andrews said.

The Japanese automaker also experimented with a system that would direct sound towards people in front of the car.

He used sensors in the car to identify people and an array of six speakers in the front allowed him to issue a warning directly to anyone about to cross the road while letting other passersby in silence.

The project has yet to make it into a production vehicle, but it is an option when self-driving sensors become commonplace on its vehicles, Speed-Andrews said.

As rival automakers pursue different sonic paths, Zimmer thinks it makes sense to discuss a coordinated plan to avoid an urban cacophony of discordant sound and noise.

“One of the things I’m going to try to get into in the future is all the other sound designers from all the other companies,” Zimmer said. “Is there a way to find a harmonious way to do this?”

Cameras, which are becoming commonplace on vehicles, could make it possible to modify sounds according to the outside environment.

Zimmer said the first question he asked after signing up with BMW was whether it would be possible to change the soundscape to suit the setting of the trip, whether it’s the exhilarating views of a mountain pass mountain or the calmer experience of night travel.

“When I write for a movie, I write for the protagonist,” he says, “but when I write for a car, I’m the protagonist.”