Here is my take on this, and please accept it for what its worth, and that being just my personal opinion.
The first EVP file, when I first heard it I heard the beeps and thought it was my audio processing equipment. But then I realized its in the audio file itself, and must be some equipment at the site since I can hear the reverberations from the room. Also the plane which is going over makes it difficult to detect other sounds. I know you can't control those issues.
In that audio file I was able to make a reverb profile (The time it takes for reverb echos to subside, and the time from the initial sound to the first reverb hit.) It seems to be a large hall with stone walls.
I hear the whispers, but one thing I noticed is that when I apply a reverb reduction algorithm the whispers go away. Also each time I hear the whisper, there is a noise or click or sound preceeding it. I'm thinking what we're hearing may be the reverb echos from sounds or movements. At list in that particular recording. If you look at the profile of the sounds, they start pronounced and get quieter which is also consistent with a reverb echo.
In the second recording, I'm seeing much of the same thing. What sounds like a voice is repeat reverberations of the noise just preceding it. I pulled up the wave form pattern in a amplified manner, and when I did you can see the ramp pattern which is customary for reverbs. I'll post a picture of it below: