As I mentioned in my other post, it's a bit of an old school thing. I, and many others, were taught to listen to the machine working. We didn't have radios, cell phones, or any other distractions except the occasional cloud of mosquitoes or hornets in those days. If we did show up with some kind of transistor radio, it was left in the car or we were sent home. No radios on the job for us.
As a result, many older operators can tell more by sound alone what's going on inside a machine than the latest computerized test equipment. Now, with powershift or hydrastatic transmissions, computerized engine and other controls, super quiet exhaust systems and fully insulated cabs, you can't hear crap from anything with regard to how the rig is working. I think seat of the pants feel has become more important because of the loss of the noise factor.
None the less, I know of operators whom have hurt themselves or others by not paying attention whilst listening to radios or walkman. Any distraction can cause an accident to happen or cause the operator to wake up too late to prevent one. I had a buddy some years ago that was watching pit run go into a jaw crusher. In those days and at that place we were using good old DuPont dynamite for blasting purposes. Ole Forbes was about half asleep when he thought he saw a few sticks go by on the feeder conveyor. Sure enough, before he was fully alert and thinking he stuck his face over the jaw to double check -- just as the dynamite was crushed and blew.
Forbes wasn't a good looking guy to begin with. He was a hell of a lot worse looking after the rocks and dirt were blown into his face. He had to be med-evac'd and is actually still alive today I heard. Had to have an awful lot of plastic surgery you know. Lost one eye and half his lower jaw.
Job I had punching scrapers a couple of years ago -- one of the scraper hands always wore earphones listening to talking bobble-heads and music. He never paid attention to what was happening in the cut and I often had to tap him a bit to get his attention. I got tired of that after a few days and hit him going full bore in 2nd with a D9N. He paid more attention after that and we got down to business moving dirt.
So if someone is sitting fat and happy on an excavator seat bailing muck, and he has headphones on or has the cab radio blasting away with some Metallica, how does he hear a laborer yell that he's about to hit something or hurt someone? How does someone with earphones stuck in hear a final drive bearing going bad or a belt starting to rip? Hard enough to hear a person even without additional sound interfering.
Just a few thoughts and memories from an old dirt stiff.