Most sports headphones purposely allow ambient sound to go through so that you can hear danger coming your way when you running or cycling. The problem though is that it's rather difficult when the ear canal is obstructed to tell where the danger is coming from. Damson Headbones keep your ears open so can tell not only when danger is coming but also where it's coming from while you're listening to your favorite audiobook or whatever it is you listen to. Audio is transmitted to your inner ear via your temporal bones. When you really need sound isolation, simply plug in the removable earphones.
Was £75 on Kickstarter.