Shot Timer Trick
Being old, and too much shooting in my younger years without ear protection, big guns in the Army, plus 16 or so years in EOD, I can't hear poop.
With ear protection on, the RO has to tap me on the shoulder to start as opposed to using the "beep" on the shot timer. No problem unless you are practicing alone.
I cant hear the the timer unless I remove one of my ear muffs. I got it figured out. I clamp the time to my shirt instead of my belt. I start in the "surrender position" only my left, (non-firing) hand is holding the left muff off the ear, I can hear the beep.
At the beep I just drop the ear muff and go on about the business.
It doesn't slow me down yet allows me to use the muffs on both ears.
Probably others that are hard of hearing already figured this out, it takes me a while get the ideal.
Anyway try it if you can't hear the "beep" on your shot timer.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071