I don't think deafness is the same as headphone use, because people with non-transient
[1] hearing loss are used to hearing not being part of their awareness of their surroundings and compensate accordingly, and because there's a difference between not having auditory input and having extra, irrelevant, auditory input to process.
As someone with audiologically normal
[2] hearing, I do find myself habitually using hearing to add to my awareness of my surroundings while cycling. It isn't particularly useful for safety-critical decisions (you still need a mirror/shoulder check before manoeuvring), and it sometimes lets me down in spectacular ways (typically being startled by cyclists 'appearing from nowhere' saying hello as they overtake, and occasionally misidentifying an emergency services vehicle as Yet Another Van). TBH, I find hearing most useful on the road for electric vehicle spotting (they have a very distinctive sound that stands out in traffic) and
oik detection, and for early diagnosis of mechanical problems with my bike.
[1] I've currently got fluid in my middle ears due to infection, and because I'm not used to it, the fluctuations in my hearing *are* extremely distracting.
[2] My speech processing is rubbish, but that's not relevant here.
