Now, Apple has always gone to considerable lengths to make the iPhone usable for people with vision and hearing impairments. If you’re deaf, you can have the LED flash to get your attention when the phone rings. You can create custom vibration patterns for each person who might call you. You can convert stereo music to mono (handy if you’re deaf in one ear). If you’re blind, you can literally turn the screen off and operate everything — do your e-mail, surf the Web, adjust settings, run apps — by tapping and letting the phone speak what you’re touching. You...