Hearing Aid Beeping?

What does it mean when a hearing aid beeps? May be time to change the battery - battery might be dirty!
(This is not 'whistling' which usually means time to get a new ear mold.)

Be careful not to get hearing aids wet - that can cause them to get corroded - or dirty - if dirt gets on the battery - uh OH. If corrosion or dirt happens, find an old fashioned pencil typewriter eraser and gently rub the icky stuff off - keep batteries clean in order for them to work well.