Lots of people wall themselves off by donning headphones and turning on music. But when I really need to concentrate, music can be distracting - not to mention embarrassing if I forget myself and start tapping or swaying. So I was intrigued to learn about an app launched earlier this year as Hear, which takes the chatter and clatter around you, or from you, and turns it into a wall of ambient, if unmelodic, sound.