John Gregg Deaf?

The following link says, in its list of interesting facts about the deaf, that John R. Gregg was deaf.  I would be very surprised if this were true, especially since Gregg shorthand is phonetically based, and many deaf people have no concept of phonetics.  In one of my American Sign Language classes, I read a book about the many famous deaf people in history.  Admittedly, the text was not comprehensive, but I do not recall his name being included.

(by johnsapp for everyone)