iPhone for those deaf in one ear – Tom Cole:
The “assistive” technologies for iPhone 3GS don’t stop there. As someone deaf in one ear, iPhone 3GS is the first iPod where I can tell it to mix all sound into both channels (essentially, stereo->mono in both ears). This lets me use the headphones of my choice (current Apple’s “in-ear” model) and get all the sound in my sole functiioning ear.