I would love for the species to develop Telepathy. Since I was a child I've dreamed of the day (sci-fi drove me there), and I feel that we inch closer and closer as the Internet grows by day ..
My father (and no doubt me at some point) has hearing aids that have bluetooth in them. He can answer the phone and talk on it without an additional earpiece. Cochlear implants can be augmented to use it[1]. So at some point understanding how to inject sound into your head will become so well understood it will simply be a matter of how much you're willing to spend.
[1] http://www.medel.com/us/bluetooth-wireless-connectivity-and-...