Pedestrians wearing headphones who are unaware of their surroundings pose an accident risk for cyclists—especially if those pedestrians are blasting their favorite tunes in noise-canceling headphones that block out the rest of the world. A new bike bell is designed to pierce that bubble.
Škoda, a Czech automaker, calls its new DuoBell an analog solution to a digital problem. It’s a mechanical bell, but the company says its the first to engineer a sound that specifically tricks a headphone’s algorithm.
The Active Noise Cancellation (ANC) technology employed in headphones works by detecting outside sound and playing back an inverted signal that cancels it out. The DuoBell works by emitting two sounds the headphone can’t cancel. One sound is designed to be within a frequency in ANC’s narrow blind spot that it can’t invert, and another is too fast and confusing for ANC to process.
Škoda partnered with researchers at the University of Salford in England to develop the DuoBell. The company also worked with creative agencies AMV BBDO and PHD on the concept, and production company Unit9 helped build the prototype. Škoda says it plans to make the underlying findings of its research for the project public.
“Bicycle bells have remained almost unchanged for over a century, but the world around them has not,” Ben Edwards, an executive creative director at AMV BBDO, said in a statement.
The team determined DuoBell’s frequency using acoustic testing that found headphones with ANC had a hard time scrambling sounds in a narrow frequency range between 750 and 780 hertz. An additional resonator (which is why the bell is named DuoBell) produces an even higher-frequency sound at a rapid but irregular rhythm to further confuse headphone algorithms.
The need for a smarter bike bell comes as cycling and noise-canceling headphone use grow simultaneously. Škoda cites a 24% increase of cyclist-pedestrian collisions in London in 2024, where up to half of pedestrians wear headphones. In the U.S., injuries to pedestrians wearing headphones more than tripled in six years, researchers at the University of Maryland found in 2018, while elevated gas prices today are pushing more Americans to travel by bike or scooter.
Škoda, which is known for cars like its best-selling Octavia, a compact hatchback, actually started as a bike manufacturer, and today it’s a Tour de France partner. The company says it designed the look of the bell as a tribute to its design language, with colors, materials, and finishes inspired by its cars.
Researchers found the bell had a reaction distance of up to 22 meters, or about 72 feet, giving pedestrians crucial time to realize they’re stepping into a bike’s path. The DuoBell also underwent real-world testing trials with Deliveroo, a U.K. delivery app, and Škoda says couriers asked to keep it after the trial. Cyclists might not have to keep shouting at zoned-out pedestrians for long.