Personally I can't do it. Too much going on around you in the bush or forest when on an mtb, whether animals, tires breaking traction and concentration overall for me. When I ride I get lost if you will. On the roadie too, there are cars to mention but one danger but on crap roads with steeps descents again listening to your bike helps.
I reckon maybe one earplug of music may be ok but not two. Tried it once doing laps on the bully with left ear in, and none in right, and was singing James Brown out loud when passing a group of ladies training. Get up get on up, get up get on like a sex machine, almost got me shot by these ladies until I explained what was going on. So you see I can't do it.
I am unable to multiskill per se without getting in trouble.