Hearing being a "logarithmic" sense and decibels make this a bit weird to me. Like losing 6 dB of hearing in a car crash is considered negligible and insignificant, but that actually means the ears lost half their sensitivity in a flash (and it's never coming back, just like teeth). Likewise your 50 dB hearing loss is considered moderate, but actually represents a 300-fold reduction in acuity.
Although I try not to think about that too hard because... well it's kind of depressing.
But it's the exact reason that hearing aids are so difficult to design.
For example if you were to naïvely try to just "add back" 50 dB of gain to a 70 dB ambient sound, that hearing aid would be trying to pump 120 dB of sound energy into your ear canal... which would actually cause damage to the surrounding cochlear bands...
But if it doesn't try to add something there, then everything sounds distorted because you have way too much sound energy from the other frequency bands, perhaps ones where you have much higher sensitivity.
Hence the multi band compression and why it's so difficult, and why hearing aid manufacturers focus on speech intelligibility above and beyond everything.
