The notes from the 2009 BFRO expedition to Pennsylvania were finally published on their discussion forum:
and in that thread the expedition organizer shared a couple of howl recordings he describes in the notes. I made a couple of spectrograms for these two recordings and noted a couple of things worth pointing out.
1 - the howls come three at a time and start high, then drop in frequency, and
2 - the howls start at or just below 600 hertz
3 - they lack the bark or warble common to many coyote howls
600 hertz is the low end of the coyote howl spectrum, with only a few recordings in my collection that go lower. In fact coyote howls in these same recordings are above 600 hertz. Calls below 600 hertz are more frequently associated with humans, wolves, dogs, or suspected sasquatch howls.
The howls are here:
and the associated spectrograms are here: