ASIL
Search for "nerve deafness".
You will find heaps on ear ringing. eg
http://member.rivernet.com.au/balehi...eOlderEars.htm
I have had ND for years due automatic weapons. I wear a DC 10 34 headset which is a great help. I did not help myself when I started flying as that was the pre-headset days and there is a lot of low frequency noise in aircraft. Nor with the audio headphones on and the stereo thumping out Bob Dylan or the Doors, and attending Dire Straits concerts. It all adds up to incremental damage.
Years ago we used to camp 60 miles from the nearest town and I always used to tell Jen there must be a homestead somewhere within 10 miles coz I could hear their generator at night. There was not - I hear the same noises when I fly into quiet Outback locations and stay overnight - the tinnitus is what I am hearing.
These days I carry a pair of ear inserts in my wallet and they go on near any significant noise. I suggest this is wisdom for any pilots.
I have a digital hearing aid - I hate it and it brings up a lot of background noise also.
Downsides of ND - cannot talk to people at loud parties, sense of being overwhelmed, and don't hear vowels and soft consonants so have to fill in the gaps - bearded soft spoken people are almost a communication impossibility. It also affects my balance, add alcohol and gravitational deprivation is highly possible.
Positives - semilipreading means you focus on peoples faces and they trust you accordingly, you can decide when or not you wish to hear the missus, the new stereo can be purchased in mono at the Op shop rather than a Bose, and you hear the attack helos earlier because the birds twittering etc is not in your audio range.
Seriously, it's a fair barsteward. You only get one pair and I suggest you do all possible to look after them.