The screams don't really sound as if they could come from either man, they do sound like a woman or a child as they are so high pitched.
But to be fair, I have only heard one man scream for his life ever, when I was a lifeguard and he was drowning...he was more yelling than screaming; "help---hey" stuff, not literally screaming.
I probably believe in voice recognition, but find it less believable as you move from the range of speaking or talking loudly. I know so many who, for example. sing well but it sounds SO different from how they speak. I just don't believe a scream without any words can translate, no matter how fancy the technology. And even now, there is basically a 50% chance it is Zimmerman, so I find this "evidence" pretty much a non-issue.
Again, as i sit in San Antonio where just yesterday 2 were killed by a drive by shooting while attending the funeral of a young gang member, I can't understand why this one case in a sea of tragic cases is getting so much attention when the bigger question should be, "How do we keep gang members (of all races)from killing each other?"