Deafness is a huge handicap, in many ways significantly worse than blindness. That the victims of this horrible ailment start to self identify with it isn't a reason to subject new humans to it.
The idea of it being genuinely difficult for a person to be warned or notified is terrifying. Put your phone in your bag and you might as well have left it at home. Honking, people yelling or screaming for you to move out of harms way, even air sirens... You'll have no idea.
All the infrastructure that would support deaf people (like additional signal lights, vibration signals, subtitles...) are also very helpful for everybody else in specific situations.
Everybody is handicapped part of the time
What are important rooms?
> Most people have there phone on silent/vibration anyway and recently everybody uses noise-canceling headphones outside to not be bothered by other people...
> Everybody is handicapped part of the time
A phone on silent still blasts public safety warnings at full volume. A phone on vibrate can still be heard. Noise-cancelling headphones still let the outside through at a lower volume.
Very different scenario.