Hi @finnian,
I like to think of mead as an opportunity to create a tincture. This is because the mead, just as with any other alcohol-based preparation, will extract more of the active medicinal components than a simple water-based preparation. This being the case, any herbs which are commonly prepared in tincture form can also be prepared as a mead. You'll have to tinker to get the proper flavor balance, but Siberian Ginseng (Eleuthrococcus, 五加皮) might be a good place to start. You might also try Goji Berries (枸杞子) or Shu Di Huang  (熟地黃), as these would potentiate the ferment itself. In a forthcoming post (this coming week), I'll add a classical recipe for an alcoholic beverage made from a combination of the two. 

In any case, I recommend you try a tea (decoction in water) of any herb before you take the time to prepare it as a mead. No point in putting the time in if you don't like the flavor ;)

Chinese herbs for hearing loss typically involve formulas which address the underlying pattern rather than the specific condition. This being so, it's a bit hard to recommend one herb or another without knowing more about your particular case.

It is not my intention to use steemit as a sales platform. Nonetheless, I *can* prescribe and ship herbs (in the lower 48, USA) if you'd like to consult on a more formal basis. If you would, please follow the link to my website for contact info.

In any case, for *generalized* nerve damage, one of the best herbs is Ashitaba. It can be a bit expensive, so I suggest growing it yourself with seeds from https://strictlymedicinalseeds.com/?specific=jrennrf0
(I have no affiliation with this company other than as a satisfied customer.) Lion's Mane Mushroom is also helpful in this regard. 

Cheers!