At least at Mac OS X. If I remember well, it was the question to change that, because of licensing issues and eventual conflicts with rtAudio.
OF 0.9.0 will still be using fmod, at least on windows. afaik there wasn’t a push to depreciate it for this release but I know there is an open issue on the github from a bit ago
There is an open PR to use Open AL with MSYS2 that was a little too late for 0.9.0. But it is scheduled for 0.10.0.