Stats in the USA. reveal 79,000 claim SS, out of 1m deaf entitled to it. By comparison the UK has that number claiming, despite having far less than 79,000 deaf people.
About 40 years too late for the UK, as Deaf are advised to use disability support areas and the CAB and neither have the funds to provide signed support, and the BDA hasn't any trained staff in Wales to help a deaf person, they told them to ask the blind instead. What happens is the 'access bank' of Mum and Dad who know even less than the Deaf do, and invalidates their claims.
It goes without saying signed support to claim SS benefits isn't there either. It is why 46% of UK deaf people all lost their entitlement to it. I have no idea what 'legally deaf' means either, as everyone is deaf here if you have hearing loss !