Making Birch Bark Extract?

I was wondering if there were any good recipes/info resources for making a birch extract for making soda? Is it as simple as simmering the bark in sugar syrup a la Alton Brown? I've always wanted to try this. We have a lot of birch trees growing in the backyard, and I've noticed whenever I cut one down that it gives off that nice root beer-like aroma.

I'm hardly an expert, but my understanding was that extracts were made by soaking your extract ingredient in vodka/brandy/whiskey for a few months. If that's the case, the idea would be to rough up some birch bark then soak in a mason jar of alcohol.

I'm a total newb to the whole soda making thing, so perhaps extracts are different in this case.

If you're thinking of something that's more on the sweet side, perhaps you might try Birch Syrup?

What variety of birch tree do you have?