Originally posted by BackFire
That sounds less credible considering the ones saying that it is not Zimmerman are based on Zimmerman's actual voice samples in comparison to the voice screaming in the background. Where as the one you mention is based off of nothing, because as far as I know, and I could be wrong, there is no actual voice sample of Trayvon Martin at this time to compare it to, so it's based on an assumption of Martin's voice, vs the actual voice sample of Zimmerman that shows it is not him.
That's not a conclusion that can be drawn based off of what I have told you. You cannot determine which one is more credible than the other.
The one I mentioned is based off of a whole bunch of forensic data including matching age to humans. The age of the voice is probably the number one issue, here.
Additionally, the match was said to be at 48% to Zimmerman's voice with no match to Trayvon due to a lack of samples.
The news organization, The Sentinel, contacted Owen. Owen used a software program, Easy Voice Biometrics, in his analysis to the 911 calls for help.
Owen said: "I took all of the screams and put those together, and cut out everything else..."
"As a result of that, you can say with reasonable scientific certainty that it's not Zimmerman..."
The software returned a 48% match to Zimmerman.
Here's the key:
Owen said to reach a positive match with audio of this quality, he'd expect higher than 90 percent.
While I am not near as versed as Mr. Owen would be, I do have real world forensic experience in digital audio analysis. That's my major: digital forensics. I have 2 classes left and I graduate (Discrete Math and a speech class).
In order to be an audio expert, like Owen, you need quite a bit of acoustic based biology under your belt. You're supposed to be able to tell the difference, with digital audio tools, between an 18 year old female bonobo (Pan paniscus) and a 13 year old female common chimp (Pan troglodytes). What the audio analysis will do is allow you to discern that both are females, but one belongs to one species and another to the other. It will finally be able to tell you a general age and you should be able to tell that the bonobo is a few years older than the common chimp.
It takes training and lots of practice with the vocalizations from each to get a knack for it. You would compare samples in order to reach this conclusion. Samples from the same animal and same species, to be exact.
Now, in order to say it was zimmerman, we need a much higher certainty. I looked for about 3 minutes for the other analysis that showed the voice was not a young man, but a man around 30, but I could not find it. It has been buried underneath google's preference on the search engine: it is showing only stuff it thinks I want to see so I may not be able to find it with google. I'll check again, but I just do not have websites off the top of my head that are pro-Zimmerman in this case.
It boils down to this: the same audio specialist, Owen, also concluded that Zimmerman said "punks" and NOT "coons". So what can we say about Owen? I say he is being fair and unbiased. I, personally, am not quick to dismiss Owen's expert opinion. If we accept that it matches Zimmerman's voice at a 48% match (meaning, not likely, but still a significant percentage enough to leave a bit of doubt), and that he said "punk" instead of "coon", then we are left with sh*t...still. More doubt and more confusion.
Throw in the fact that the witnesses contradict each other (some say Trayvon went apesh*t straight away, some say that Zimmerman was aggressive and caused the fight), this case becomes even more confusing.
Then throw in that Trayvon's own father said the one yelling for help was not his son, and the audio expert opinion may become questionable:
http://news.yahoo.com/video/orlandowesh-16122564/what-is-a-second-degree-murder-charge-28936372.html
Throw in the fact that Owen said that even if under duress, the voice-fingerprint (we each of a fingerprint, so to speak, in our voice...but it is not as clear and varied like an actual fingerprint) is still discernible. It is NOT (I do not know how much I can stress how wrong Owen is, here) that clear cut. Sure, some of the voice elements may still show up (multiple will, in pretty much every vocalization) but it can radically change the "fingerprint" of the voice greatly affecting the outcome. You must use an apples to apples comparison when doing these things to create a "sure" comparison. This is called spectrographic forensics. It gets even more troublesome than just doing an audio analysis with expensive audio tools: you go as far as to inspect the magnetic tape, under a microscope, to check for tampering because you must verify authenticity before it can be considered admissible evidence. Yes, some dude busts out the magnetic tape in a dark room/clean room, puts it under a microscope, and reviews key/transitional portions of the tape for tell-tale signs of tampering (including re-recording).
There's more...
Additionally, linguistic syntax is also used in the analysis and a profile can be created to see how likely someone is to "match" a recording. We have weird and unique ways in how we use our words. This does not apply to this case (I do not think) but it is also something considered in when reviewing.
So with one expert claiming a 48% match, meaning "not likely", but also showing us that Zimmerman said "punks" not "coons", I still do not know what to think.
Is it possible that Zimmerman asked for help at some point, too? Meaning, did both call for help and Trayvon didn't call for help until right at the end? I don't know, but it is possible.
I know I could recognize both of my children screaming in a sea of screaming children...if I were totally blind. As parents, you get used to your children's voice and you subconsciously do your own audio analysis and match. I would tend to think Trayvon's father's opinion on who it was screaming is fairly important. I do not know if it can be considered a definitive defeat to pro-Trayvon camp, though. All it means it the Father does not think the yelling voice is his son's.