Skoda Auto DuoBell: bike bell that remains audible even through noise-cancelling headphones

Skoda Auto has introduced an unconventional approach to urban safety with its DuoBell concept — a bicycle bell designed for an environment where pedestrians increasingly isolate themselves from surrounding sounds using ANC headphones.

The project was developed in collaboration with researchers and audiology experts from University of Salford. Its primary goal is to reduce the number of incidents between cyclists and pedestrians who fail to respond to traditional warning sounds due to active noise cancellation.

Focus on sound perception rather than volume

Instead of simply increasing loudness, the engineers focused on frequency selection. DuoBell produces sound within a narrow 750–780 Hz range — frequencies that, according to research, are less effectively suppressed by ANC algorithms.

The design also incorporates a second resonator and a mechanism that generates irregular sound pulses. This makes the signal harder to filter out, as noise-cancelling systems typically perform better against consistent and predictable sounds.

Real-world testing results

Tests showed that pedestrians wearing headphones reacted to the signal earlier compared to a standard bike bell. On average, this provided up to 22 meters of additional reaction distance.

In dense urban environments, such a margin can significantly reduce the likelihood of collisions.

Fully mechanical design

Despite its innovative concept, DuoBell is entirely mechanical. It contains no electronics, batteries, or digital components — its effectiveness relies solely on acoustic engineering and physical construction.