So he is doing just that when he realizes that in fact, it's not possible, and that he needs to take the headphones off. He politely says "miss?" There is no answer "Ermmm, Miss?!" Still no answer. He tries again a few times, but still nothing happens. So he decides not to waste his time anymore and he just removes the headphones until he's finished working (making sure he works as quickly and cleanly as possible.)
To his horror, when he looks down at the young lady again, he finds her quite dead. He wonders how taking headphones off someone's ears could make them drop dead. And then is glad that the shop is quite empty (as it always was.)
Getting curious at last, he puts on the headphones, and is terribly intrigued by what he hears:
"Breath in, breath out, breath in, breath out, breath in, breath out�."