One thing to remember is that what we hear when you speak is not necessarily what you hear.

We (and by that I mean me) hear the difference between the way we say something and the way you say it. That means that you can listen to yourselves night and day for a year and have no idea what it sounds like to me(I mean us). Which is probably as it should be.

I grew up in Michigan, and spent time in Canada, and even worked in Canada with actual Canadians. I can tell you right now that, though in a couple places we are actually only a walking distance apart, we talk real different.

For one thing, you are careful about the sound of letters like "t". Not us. We tend to use a glottal stop instead. That would be the sound of the hyphen in "uh-oh!" In music, it would be a stacatto rest. We also stretch out our vowels, sometimes for two or three syllables. Usually just two. And there is a certain nasality.

If one were pressed for a description, with a view toward helping someone identify it, I would suggest imagining a person with a sinus infection talking to a deaf person.

So we hear "oot" because we're used to "oww' ".