Though, thankfully, we didn't have to use this product in the wilds of Canada we did test it to see how far apart we could get and have it still be heard. It worked fine and we were able to hear from a long distance away.
I am a Land Surveyor and I use the compass on a daily basis. The compass works great to get a ballpark direction. My only complaint is that the thermometer has too large of range with too few graduations. It's only good to the nearest 5 degrees.