Academic research in a nutshell: the mysterious sound of flashing lights

Are your senses playing tricks on you? The latest research from City academics suggests they could be

A researcher at City has found that a surprising number of people hear a noise when they see a completely silent flash.

Tell me more…

Dr Elliot Freeman is a cognitive neuroscientist at City. He recently found that one in five people experience a ‘synaesthesia-like phenomenon’ — which means they hear a sound when they see silent flashes of light.

Synaesthesia… the 80s glam rock musical instrument?

No that’s a SYNTHESISER.

Synaesthesia is a condition where a sensation in one of your senses (like hearing) triggers a sensation in another (like taste).

For example, if you had synaesthesia, you might be able to taste the number five, or days of the week might appear as colours.

Synaesthesia is rare — it affects just 4% of the population. The ‘flashing light’ thing is a milder version of this, but is much more common.

What kind of silent flash are we talking about here?

A morse-code style light flash was used in the experiment. But it could also apply to things like disco lights or a pelican crossing, a lighthouse. A baby toy with flashing lights, strobe lighting at a club….That kind of thing.

So what noise do people hear when they see these flashing lights?

Usually a faint sound. A hum, a whoosh or a buzz.

How does this happen and why?

Elliot reckons it’s all down to the close link between the parts of your brain that are responsible for hearing and seeing. The overlap between the ‘hearing’ bit and the ‘seeing’ bit results in a very slight merging of the two.

Hang on. If this is happening to so many people, why have none of them mentioned it before?

Quite often, movements or lights are accompanied by a related sound; so many people might not even notice it happening. In fact, this could be one of the reasons it happens; because sound and vision are naturally related.

If I hear flashing lights, does it mean there’s something wrong with me?

No! As we mentioned earlier, it’s quite common and there’s no evidence that this means there’s anything wrong with you.

The School of Arts and Social Sciences have created a short test to gather more data about the phenomenon. Take the test to help them out!


Academic Research in a Nutshell is a blog series aiming to explain some of the excellent, ground-breaking research that happens at City in a simple, bite-sized way.

For more information about this research visit the City, University London webstory: Synaesthesia ‘hearing-motion’ phenomenon more common than previously thought, says study.

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