Happy Thought for 10 April 2026

Have a Happy Thought:

Sometimes the only way to keep your sanity (or hearing!) in a noisy environment is to wear noise-cancelling headphones.

Sometimes you just want to wear noise-cancelling headphones to hear your music/podcast/phone call/whatever more clearly.

Either way, if you are out and about while wearing these, you may find that you are missing some important noises that you wish you had heard.

This is increasingly a problem where bicyclists and pedestrians share spaces. 

One car company (yes, you read that right) has come up with a solution: a two-toned bike bell that can cut through the noise-cancelling technology and let you hear the “ding” anyway.

Without making the bell louder.

You see, Noise Cancelling headphones work in a couple of different ways.

First, the big foam earcups or well-fitting silicone or foam earpieces. These physically insulate your ear canal from sounds coming from the environment.

Then, you can have Active Noise Cancelling – and this is where you might need to remember back to high school physics. Sound is actually waves of energy traveling through the air. What Active Noise Cancelling does is it has a microphone on the outside of your headphones that “reads” that wave, puts it through a computer, and nearly instantly creates an equal-and-opposite wave. The two waves then cancel each other out:

Image: PC Mag Think of noise cancellation as being where the blue and green sine waves meet on this graph, cancelling each other out

It’s the calculation process and the creation of the opposite waveform that a) makes it Active (rather than Passive) Noise Cancelling; and b) is why your headphones use more battery power when they are in this Active mode.

The need to calculate the equal-and-opposite wave is why Active Noise Cancelling is really good combatting continuous or ongoing sounds, like your office’s HVAC system, or airplane engines. But a sudden sound, like a car backfiring, will still get through to your ears.

Even within the Active Noise Cancelling process, there is a “blind spot”, where existing headphones struggle to create the calculation and opposite-wave:

Image: University of Salford / Škoda Auto

So the scientists and engineers looking into how to make a better bike bell put the two weaknesses together, to create a bell that

a)  Makes a sound in the “blind spot”, and

b)  Creates higher-pitched (in a normal bike-bell range) sudden sounds

Oh, and did I mention that they declined to patent the tech, instead sharing the science and research openly, so it’s free for anyone to pick up and make their own improved bike bell?

 

 

If you want a cool video-explainer of this, check out Dr Hannah Fry going through the physics https://youtube.com/shorts/Hwn3gJ9xw1M

You can read the university research that went into the design: https://cdn.skoda-storyboard.com/2026/04/Skoda-DuoBell-Research-final_cf127752.pdf and figure out how to make one yourself

Or, you can just buy one.