That's already been proven false.
Just listened again, and yes - FALSE. The sound effects at the end of TCOT are (or meant to sound like) nature sounds, like a marsh or lake or bog or swamp, with birds and frogs all around, water waves splashing on a shore, etc. etc.
Then I played the Keyboard Stem for OTBOA (so GLAD I got those), and it's definitely MorphWiz sound effects, not nature-y at all. It sounds like synth sounds with weird unintelligible vocals as weird samples, with some interesting looping effects thrown in.
-Marc.