VOICE RECORDINGS LIKE FINGERPRINTS
Peoples voices are almost like fingerprints.
Let Zimmerman reproduce the sound of his scream.
Make or Let him do it several times. Even with him hearing it right before his performance (you don't really NEED to let him).
I am asserting that he could probably not be able to reproduce it no matter how many times he tried.
If the scream were him he would nail it easily every time he tried.
If he were a trained singer with a 3 octave range maybe he could,
but in a scream Its almost like blowing air into a coke bottle.