Gee, maybe no one should be using interactive communication while a vehicle
is in motion.
As far as deaf people driving, I have severe hearing loss, so any outside auditory
distraction makes my job of driving safely even more difficult. If you're hard of
hearing, you compensate by greater visual attention as Dave said. If you have
normal hearing, your other senses don't compensate, so in a sense, you're driving
with a sound distraction.
Driving is a full time, full attention required job. If you aren't paying full attention,
you're impaired.