It is more or less based on OS X audio, yes. The author of the Web Audio spec previously was an architect on Core Audio at Apple. He basically moved over to Google, implemented his chosen subset of Core Audio in webkit, and shipped it prefixed. Then the evangelism group got big players like Rovio to ship apps that depended on the half-baked prefixed API so it was the de-facto standard for game SFX on the web.
Interesting! It's surprising to me that Apple (or Google?) is behind such a poor API, after Apple did such a good job with both Canvas and CSS animation.
