I can't speak for the animals, but I can definitely vouch for the air traffic noise in Yosemite and various other spots.  I try to tune it out, but it's tough to really feel like you're in the wilderness when the sounds you hear make you feel like you're in the suburbs.

It's similar to the issue of light pollution (and one wonders what impact this has on wildlife as well).

Not to be too pessimistic, but it's a discomforting to think what this planet could be like 100 or 200 (or even 50) years from now, seeing how much it's changed in a few decades.

For years I ranted and wrote screeds about jet noise pollution over "my" wilderness areas in the TN and NC mountains.  No one seems to care as most people are either indoors or in those jets.  I wonder what it will be like when each person has a "flying car"??

Then there is the recent hellish phenomena of motorcycles racing on roads below the mountain peaks and causing all sorts of racket which can be heard for miles.  Mufflers?  Naw, don't bother them with the idea of using mufflers.  The head honchos wring their hands in anticipated greedy joy at the thought of having technology dominate nature, and this is easily proven by the increasing noise pollution (not to mention air pollution) in our forests.

Air pollution?  Well, the stink is terrible and of course the Smokies has the worst air pollution for a national park in the US---as bad as Los Angeles.  And yet the top tiered alpha dogs still let in endless car traffic with bumper to bumper Cades Cove rolling couch potatoes.

In the Oregon dunes ATVs cut down signs saying no ATVs. Most times there is a new path into the area right next to the sign. These are my camping areas. And even miles into these areas ATVs speed around. I was once camping around 5 miles in, and one morning I heard the roar of a ATVer. He jumped over a small hill and landed 5 feet from my tent. He stoped and gleered at me like " what the heck was I doing there?". He sped off saying nothing.