It was roughly six years ago when Audi started designing bold soundtracks for its growing line of hybrids and EVs. Why did the 111-year-old carmaker need custom sounds for its forward-looking product line? It all comes down to one thing: electric vehicles are practically silent, even when traveling at high speeds.
The idea of silent cars might seem exciting if you spend your days walking beside noisy urban streets, but quiet cars have a couple of drawbacks. For one thing, they're dangerous to pedestrians and other drivers. That's why most countries have a series of regulations that set acceptable ranges for the volume and pitch of the noises that EVs have made. Another down of noiseless EVs is the driving experience. A full-bodied roar makes driving more fun.
For Audi drivers, that's where Stephan Gsell comes in.
Early experiments led to Audi's distinctive approach to sound design
Engineer Stephan Gsell was brought on to design the company's first sounds for its Q7 Hybrid series. "We needed a sound for when it was driving electrical," Gsell said. At first, they made the obvious choice and tried to recreate the sound of the vehicle's internal combustion engine. Since they started with a hybrid, there was a template inside the car.
"That sounded quite nice, but after a while, we figured that it probably wasn't what the customer wants to have," Gsell said. Car designers in the past had to put some thought into how their vehicles sounded (you don't notice the muffler until it's gone), but Gsell and his team were some of the first to design the sound of a car from the ground up.
"So we created something new. We started developing something else that isn't a copy of the combustion engine but also isn't a copy of a spaceship," he says. "We had to find something in between because it's a car and not a plane."
They weren't making the "Audi sound." Every hybrid and EV in the company's lineup has its own sound, custom-designed by Gsell and his team. "What we like to say is we like the car to choose its own sound," he said.
Speed determines how the sounds are played
Designing a car sound is an unusual kind of audio production. Like a movie soundtrack, the car sound operates in the background and supports a visual element that viewers are more consciously aware of. Unlike a movie soundtrack, the car sound doesn't change with time. It plays according to speed.
The production process starts off in a conventional way... sort of. The sound designers record several sounds that will collectively make up the final production. For a rock band, it would be like recording guitar, bass, drums, and vocals. And Gsell and his team do occasionally use a guitar. But instead of playing it, they put an electric drill parallel to the pickups, hold it a few inches above the instrument, and record the bizarre sounds of its magnetic field interacting with the pickups.
Once all the recordings are collected, they use custom software to mix the sounds. But instead of making a linear track, they create the 32 soundtracks that an Audi draws on to create the sound at any particular moment. "We have options to equalize them, like by increasing or decreasing frequencies. Then we mix them all together to get the output on a speaker that's usually in the front of the car, somewhere under the hood," Gsell says.
After a lot of tweaking, the soundtracks — they're different depending on the jurisdiction where the car is sold — hit the streets. There's a good chance you've already heard Gsell's work driving down the streets of your city.