Hearing aid funtional benefit outcome

[Jay Hans]

Looking for anything in the literature on measuring functional outcome
benefits of hearing aids on the minimally hearing impaired.  Primarily
as in: when should an insurer pay for a hearing aid when it's benefit
is questionable but not impossible.  With aids costing upwards of
$3000 a pair this question is no longer moot.  This must be a
measurable outcome not a "warm fuzzy".