Electric vehicles have made a name for themselves as gas-powered cars’ greener, quieter alternative.

But not too quiet.

Without a noisy internal combustion engine, electric cars are required to emit artificial sounds at certain speeds so pedestrians are aware of approaching vehicles. But exactly what that alert system sounds like is up to the discretion of automakers.

Fighter-jet-inspired roars? Spaceship-sounding whirs? Classical-music-inspired tunes? They’re all on the road.

As a newer field, “EV sound design is wide open,” General Motors Regulatory Sound Engineer Glenn Pietila told USA TODAY. “There's a lot of different directions people are going.”

Rules of the road

The National Highway Traffic Safety Administration says new electric cars and hybrids must emit noise when operating at speeds below roughly 20 mph. The sounds are meant to alert pedestrians to a vehicle’s location, speed and direction of travel before natural sounds – like tire and wind noise – pick up at greater speeds.

“For pedestrians who are blind or vision-impaired, sound emitted by individual vehicles – as opposed to the general sound of moving traffic – is especially critical,” said NHTSA spokesperson Lucia Sanchez.

There are some lines automakers can’t cross. Tesla's "Boombox" function, for instance, is no longer allowed to blast ice cream truck jingles, clacking coconuts, or fart noises while the vehicle is in motion after U.S. safety regulators said the sounds could drown out pedestrian alerts.

And pedestrian warnings must meet minimum sound pressure levels and have the same sound across all cars of the same make, model, year, body type and trim, according to NHTSA.

Otherwise, manufacturers are free to get creative.

Sounds of the road

At General Motors, sounds vary across the automaker's four core brands: Buick, GMC, Chevrolet and Cadillac.

Creative sound director Jay Kapadia and his team used a didgeridoo – an Australian wind instrument – and sounds recorded from the sun to build the melodic tunes of its electric Cadillacs. Electric GMC Hummers, meanwhile, are more loud and grungy, so “you know it’s a big truck,” Pietila said.

“Both of them fit regulations. When you hear them, you know they're there. You know that there's a vehicle there that's approaching,” Pietila added. “But you also know what (brand) it is. You know, it's a luxury car, it's a Cadillac, even if you can’t see it.”

For Dodge, the Stellantis-owned automaker was inspired by engines like the V8 when designing the sound of its Charger Daytona EV. The car’s “Fratzonic Chambered Exhaust” system is meant to create a "deep rumble and visceral feel" similar to traditional, gas-powered muscle cars.

“Our approach was familiarity, consistency,” Dodge brand manager Kevin Hellman told USA TODAY, adding sound “is synergistic to the whole muscle car experience.”

It's "really interesting" to see how automakers are tackling the sound requirements ‒ especially performance vehicle manufacturers like Dodge, said Cameron Rogers, a news manager at market researcher Edmunds.

"How do you convince your customer who doesn't mind a five-mile-per-gallon car into an EV switch?" he said. While a certain kind of driver may be hesitant to drive an EV due to a lack of visceral feel, "these sorts of things could definitely persuade them."

Drivers of the Hyundai Ioniq 5 N have options, with three soundscapes that can be played inside and outside the vehicle. The automaker says one theme simulates the sound of an internal combustion 4-cylinder engine, another offers a "high-performance sound" and the third was inspired by twin-engine fighter jets.

“The ultimate goal is to have a sound that is authentic, even though it might not always be realistic,” said Taylor Marotta, a senior noise, vibration, and harshness engineer at the Hyundai Kia America Technical Center. “This goal is shamelessly borrowed from sound designers of movies and video games. No one has seen a starship scream through space, but you need to make sure it sounds and feels right to the viewer.”

Other automakers' approaches to EV sounds vary. BMW partnered with Hans Zimmer, the composer behind the film scores for “Dune” and “The Lion King,” to design the sounds for its i4 electric sedans, according to its website. Fiat has its 500e sing a digital melody at certain speeds meant to share a "taste of Italian culture," according to a March news release. And some hybrid backup alerts have been compared to spaceships or a chorus of angels in online forums.

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Leslie Klieger, 51, of Fanwood, New Jersey, likened her 2024 Honda CRV hybrid’s backup noise to a “celestial choir.” While the noise is loud enough to embarrass her teenage son at school drop-off, she said she loves everything else about the vehicle.

“When you're backing up, there is no question about it. No question at all. You know I'm there," she said.

Honda spokesperson Brad Nelson said the automaker's electric and hybrid vehicle alert sounds meet or exceed regulations "with a reasonable margin, with proper durability to handle a multitude of environmental conditions, all at a cost that doesn’t unfairly burden customers."