I came across this in LA recently. Didn’t know what it was at the time, but a bit of Googling resolved the issue.
It’s HearWear, and they say: “wearable visual reflection of your auditory surroundings. It perceives sound levels and uses a scale of lights to reflect amplitude in clothing or accessories. The level of light depends on the level of sound; the louder it is, the more your apparel lights up.“
And then: “The electronics are seamlessly integrated in the wearable design – the sound-detecting sensor is subtle and unnoticeable, and the LEDs and electro-illuminating wire are embroidered in the transluscent textile. The developed system can be applied to any wearable items – be it skirt, bags, T-shirts, jackets, pants and belts.“
I quite like the idea, but I’m a little concerned I’d be confused for a traffic light, or for a neon sign outside a 7-Eleven! You?