Not to threadjack, but this is a question that I've had for a while and I've been looking for the right forum to ask: are there any "open source" earbuds? I would like to take a pair of earbuds and invert the noise-cancellation curve: basically, amplify any ambient noise (with filtering of course). My grandma (not in the US or EU) is hard of hearing, and the only options available to her are random Chinese junk. I would like to try this experiment, where I just invert the noise cancellation curve and make the ambient noise louder.