I know I've only been thinking about the problem for about an hour, but seems like you could hack together a solution involving a kinect processed to do audio output for a lot less than $15 million. The kinect's range isn't 1000 ft (i think more like 10, tops) but it's a "the future will inevitably upgrade" part. Audio output would be in normal hearing ranges, no surgery required, and could be adaptable to different users.