Dec [{()}]Apr 8

Skoda developed (with the University of Salford) an all-mechanical bicycle bell that bypasses active noise cancellation (ANC) in headphones.
https://www.skoda-storyboard.com/en/skoda-world/skoda-duobell-a-bicycle-bell-that-outsmarts-even-smart-headphones/
It's tuned to 750hz, which is a "blind spot" in most ANC headphone processing.
There is also a resonator for a higher frequency, and the hammer produces irregular strikes, confusing the ANC further, and making pedestrians look behind them faster.

Video:
https://www.youtube.com/watch?v=zDaVPfpQvPI

Research:
https://cdn.skoda-storyboard.com/2026/04/Skoda-DuoBell-Research-final_cf127752.pdf

#BikeTooter

Škoda DuoBell: A bicycle bell that outsmarts even smart headphones - Škoda Storyboard

Pedestrians wearing headphones are exposed to an increased risk of accidents. In an effort to reduce collisions with cyclists, Škoda Auto, in collaboration with scientists, introduces an innovative bicycle bell whose sound can penetrate even active noise cancellation systems. In doing so, it helps prevent injuries to both pedestrians and cyclists.

Škoda Storyboard
Show threadLena Schimmel

@dec23k That 750 Hz bell that uses the 750 Hz gap in noise cancellation headphones seems to be all nice and good, until you look at the actual frequencies that the bell emits:

- 1980 Hz (missing sometimes?)
- 5040 Hz
- 9000 Hz
- 13300 Hz

The image below was created using Specdroid while playing the video.

Apr 9 at 7:36amWeb
Show threadDec [{()}]Apr 9

@lenaschimmel
So there isn't any 750Hz audible in the video?

The 1980 Hz is probably the secondary resonator, missing sometimes maybe because the rider's glove was muting it?

The higher frequencies could be harmonics or other resonances.