Hi again Eric,
The more I think about this, the more I believe it's a psycho-acoustic effect. Certainly when you are in very cold weather (and I recall that Montreal winters are brutally cold), you seem much more alert, keyed up. It's almost shocking when you first encounter really cold temperatures. So perhaps, as you've noted, it's simply that your senses, including hearing, are heightened.
I was thinking about ear buds or headphones: your body heat would keep them relatively warm and insulated from any termperature effects on the voice coils, so the effect you are experiencing is a heightened sensory perception. . .this would seem to be fertile ground for some post-grad student to investigate.