I will find out for you and let you know! But to be honest, deaf people have strengthened their other senses so that they can tell something is happening without having to hear it. I think their peripheral vision is stronger.
i worked with a deaf guy who was a civilian for the Navy and our command would not let him go aboard ship to do repairs becuase they were concerned for his safety.
Absolutely. Administration at a laboratory that I used to work installed red strobe lights in all the labs I worked it. They went off when the fire alarm was tripped. Most employers would be very concerned putting people who cannot hear well in a position where they cannot hear warnings of danger for two reasons. First is obvious, nobody wants employees to get hurt and the second is lawsuits.
Is it discriminatory? I don't think so. But does it limit the opportunities of the deaf/hearing impaired people. Absolutely.
The way I see it, you have two choices, to become a victim (which many perfectly normal people do because it is easier than taking responsibility) or look for other opportunities.