SemiliveMusic,

Many artists use In-Ear-Monitoring systems and you could say this is 'hearing-aid'

For singers this is a perfect solution, because there is no noise at all... they only hear music and own voice. Even the mix is adjustable to personal wishes.
One important 'con' : Musicians lose contact with the audience.

Deb : Thanks for your kindness in this case. I'm not old but 48 years young
Why did you get the impression something is wrong with my ears ?