I bought a pair of expensive (military-type) over-the-head aids: did not
find them satisfactory due to constant dull "roar" (probably of intrinsic/
wind/other origin). My best solution is to take my wife with me.....her
hearing is superb and her doggedness unmatched, but she refuses to rent
herself out (alas!). Good luck!
a Buaidh!
FX