I'm very accustomed to using sound to detect and track things in my nearby environment. If I'm sitting in an easy chair, that's not important and I don't mind wearing earphones. If I'm out in public where keeping track of traffic (both vehicular and pedestrian) is vital, I find the lack of audio input upsets me.
cant exercise without it....makes the time move and you can use it as a timer..like if your having a problem staying on the treadmill/stepper/elliptical or whatever you can force yourself to make it thru the song...the next day make it thru 2 songs etc..youll be up to 45 minutes to an hour quick.