This seems like a good time to mention the late Bob Weitbrecht, W6NRM. He was for all practical purposes totally deaf, but was able to copy CW. I never knew if he had just enough hearing at one frequency to hear the tone or if he felt the vibrations on the headphones on his head. Anyway, at an early age he got a ham license and that opened up a whole new social world to him. Like that famous cartoon with the caption "On the Internet nobody knows you're a dog" for him it was "On ham radio (CW) nobody knows you're deaf."
When RTTY came along in the 1950s Bob was one of the great enthusiasts and technical developers. He traveled thousands of miles promoting RTTY and helping other hams to get on the air with it. He was, I've been told, one of the main actors in getting FCC to approve the use of FSK on the HF ham bands starting in 1953. Bob was the hero to a whole generation of hams who got on RTTY before Irv Hoff came into the picture. Then in the early 1960s Bob tried to help a deaf friend get a ham license, but his friend was totally unable to copy CW. So Bob turned to telephone communication, resulting in the protocols and modem standard now widely used and called TDD.
