I dunno about most, but I definitely rely on sound more than sight in the field...it's a 360 degree sense, and it's much easier for someone to wear and use awesome camo (doesn't help you if you're standing tall in the open) than move silently. I'm willing to bet more than one person here has figured out where someone was courtesy of fabric rustling, something jingling or hitting something else (i.e. gun to vest buckle contact, etc.) a snapped twig, or BBs bouncing around in a hicap. Or been found out, for that matter. I don't think I could play with background music. But that's just me.
That being said, T7 definitely has a point about there being a time and a place for everything....a little extra noise in the heat of a firefight can't hurt, can it? And some of those examples sounded pretty epic. MP3 player + speakers + vest seems like win to me...
Anyway, just my $0.02
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