From my personal experience of 15+ years contacting with authors of thousands of "free" sound fonts: they are usually composed of sounds taken from random places, and nobody really knows who made them or what their license are. Many of them take samples from other "free" sound fonts, and chain gets larger and larger so the true origin is difficult to trace. The assemblers of the sound fonts just assume that, if they can't find a copyright notice attached to the samples, they must be in the public domain. And most likely they are not. Even if they were originally released under a permissive license, the license and authors should be maintained as a minimum. Of course, there are exceptions of sound font assemblers who correctly document their sources and licenses of each individual sample, but that's a lot of work, and most common case is just to ignore everything and assume that it will be fine. It's the true and sad state of most free sound sample libraries out there.
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)