An Orchestra in Motion, With Not a Speaker in Sight

AUBURN HILLS, Mich. — Advances in technology and changes in consumer tastes have caused antennas, eight-tracks, cassette decks and CD players to disappear from their once-familiar places in our cars and trucks.

The next thing to go might be the speakers.

But thumping bass, rich midrange and soaring highs will still be there. They’ll just be coming from the car itself.

Continental, a German auto-components supplier, has developed technology that makes parts of the car’s interior vibrate to create high-fidelity audio on a par with any premium sound system on the road now.

The approach turns the rear window into a subwoofer. The windshield, floor, dashboard and seat frames produce the midrange. And the A-pillars — the posts between the windshield and the doors — become your tweeters, said Dominik Haefele, leader of the team that developed the technology.

The result is something like an enhanced version of surround sound. “It’s a 3-D immersive sound, and you’re experiencing the music in a very different way,” Haefele said. “You’re in the sound. You feel it all around you, like you’re adding another dimension to it.”

The key components are transducers — small devices that use a magnet wrapped in a copper coil to convert electrical energy into mechanical energy. Run current through the wires, and the transducer vibrates. Continental has figured out a way to implant transducers in a car’s interior and use them to turn interior panels into speakers.

Haefele said the concept wasn’t that different from how a violin works. “When you draw the bow across the strings, they vibrate, and the vibrations are transmitted through the bridge to the body of the violin, which is what makes the sound you hear,” he said.

On a cold afternoon at Continental’s research lab north of Detroit, Haefele slid behind the wheel of a black Mercedes-Benz C-Class equipped with the system. He cranked up “Oh Yeah,” the funky 1985 hit made famous in the movie “Ferris Bueller’s Day Off,” and the song’s distinctive bass throbbed from all directions.

“You can’t tell where it’s coming from,” Haefele shouted.

Switching to Marvin Gaye’s classic “Heard It Through the Grapevine,” he pointed to the A-pillars. Tambourine and guitar riffs rang out crisply as Gaye crooned about the anguish of his betrayal.

The system, which Continental calls Ac2ate Sound, should begin appearing by 2021, Haefele said. He declined to name the carmakers that will offer it, although Mercedes, BMW and Audi are all big customers — and frequent adopters — of Continental’s technology.

The company envisions creating a basic sound system with five transducers, a midprice system with eight and a high-end system with 10. Continental also sees the system providing a new way of selling and upgrading in-car audio, Haefele said. Carmakers could build all their models with 10 transducers, and turn on only those the customer paid for. The owner could later buy an upgrade that would power up additional transducers and turn a basic audio system into a premium version.

But such integration of the sound system into a car’s interior does present some complications.

In the case of an accident, a damaged A-pillar or windshield would have to be replaced to restore sound quality, Haefele said. “But this is very similar to conventional speaker systems where the speakers are integrated into the A-pillars,” he said. Something like a chipped or nicked windshield should not affect audio quality, he said.

James Grace, a senior director at Cox Automotive who previously worked in automotive interiors, said the biggest challenge for developing speakerless audio systems would probably be eliminating the vibrations, hums and rattles that so often emanate from interior parts and properly integrating the sound-producing parts with the rest of the car.

“Interior parts are not typically made to produce high-quality audio,” he said, but added that it was a “pretty clever idea.”

And it’s not the only audio innovation on the horizon. Bose, the speaker and headphone company, is working on technology that blocks out music, navigation commands and other background noise from phone calls made from inside the car. The system, called ClearVoice, is based on the same type of noise-canceling technology Bose uses in its headphones. The company does not have a target date for making the system commercially available. In a similar vein, Faurecia, a French company that makes auto seats and interiors, is developing noise-canceling technology that would enable one occupant to make a phone call undisturbed while another continued to listen to music. Faurecia calls it “audio cocoon” technology, but most Americans of a certain age may prefer to think of it as the kind TV spy Maxwell Smart once used — a “cone of silence.” Faurecia demonstrated the audio cocoon at the International CES expo in January as part of an auto interior of the future that it is developing.

And while voice-assistant technology is already making inroads, Kia, the South Korean automaker, is working on a way to make interacting with your sound system less noisy: At CES, Kia demonstrated technology that allows drivers to control the car’s audio, climate and other systems using hand gestures.

Few in-car technologies have backgrounds as unlikely as Continental’s Ac2uate Sound. It germinated not from an effort to improve automotive audio but as part of a bid to reduce weight. Automakers of all stripes, searching for better fuel economy, strive to reduce weight whenever they design a new model. Most of the reductions come from hundreds of small changes that save a pound here and 2 pounds there. A Continental acoustics team wondered it if would be possible to turn a dashboard into a speaker.

The idea wasn’t totally far-fetched: Some cars already have transducers that create extra engine sounds inside the cabin, for drivers who just need to hear the roar of horsepower. Once the team got rolling, it tested different parts and settled on the ones that made the most sense.

The windshield and rear window are stiff and heavy, so they are most appropriate for lower frequencies. A-pillars have smaller, thinner parts that are better for high-pitched sounds.

By tuning the correct parts, Continental reproduced the experience of a top-of-the-line audio system — which can exceed 20 pounds — with parts that weigh just 2.

“It was,” Haefele said, “a little like setting up an orchestra.”