Back on the Trayvon Martin killing audio expert Tom Owen is getting good press with his claim (broken by the Orlando Sentinel) that it is not George Zimmerman heard screaming for help on a 911 call. Here are CBS, CNN, MSNBC, Mediaite and the Boston Herald.
I squawked that other experts would question that conclusion - a good forensic audio match requires examples of speech similar to the sounds being compared. So using George Zimmerman's spoken voice on his 911 call and comparing that to the screams heard in the background of a second 911 call would be a no-no for the other experts.
And Tom Owen agrees! In describing his techniques at his website, we see this: (my emphasis):
The examiner can only work with speech samples which are the same as the text of the unknown recording. Under the best of circumstances the suspects will repeat, several times, the text of the recording of the unknown speaker and these words will be recorded in a similar manner to the recording of the unknown speaker. For example, if the recording of the unknown speaker was a bomb threat made to a recorded telephone line then each of the suspects would repeat the threat, word for word, to a recorded telephone line. This will provide the examiner with not only the same speech sounds for comparison but also with valuable information about the way each speech sound completes the transition to the next sound.
There are those times when a voice sample must be obtained without the knowledge of the suspect. It is possible to make an identification from a surreptitious recording but the amount of speech necessary to do the comparison is usually much greater. If the suspect is being engaged in conversation for the purpose of obtaining a voice sample, the conversation must be manipulated in such a way so as to have the suspect repeat as many of the words and phrases found in the text of the unknown recording as possible.
The worst exemplar recordings with which an examiner must work are those of random speech. It is necessary to obtain a large sample of speech to improve the chances of obtaining a sufficient amount of comparable speech.
And this is the man who now claims that a few seconds of background screaming can be matched to calmly spoken words.
Well, if the prosecutor loses his mind and waves Mr. Owen up as an expert witness in the trial of George Zimmerman, the defense will ask him to re-read this material from his own website, then ask the judge to dismiss him. Good luck to the prosecutor.
I have no doubt that the investigators have already received this advice, so let's not hold our collective breath waiting for the audio deus ex machina. This testimony won't be credible and may not even be admissible.
As to why Mr. Owen is sticking his neck out, well, he may be civic minded. But he rolled out his new voice recognition software on March 1, so he also may welcome the publicity.
I figure the media mavens that are starting to play catch-up will catch up to this by May. Is is asking to much to expect them to review his website and ask a few basic questions, such as, why does your website say this Zimmerman match can't be done? Oh, why ask why.
HMM: In an Addendum Jacob Sullum wonders whether the dubious audio evidence, presumably in a larger context, would be allowed to help establish probable cause for arrest even if it had little chance of being admissible at trial. Over to the lawyers!
For a lighter look, from 'someguy' in the comments, I am stealing a quick Frequently Unasked Questions about Tom Owen. Imagine this as a trial cross-examination, because the prosecutor may be having nightmares about just this:
Tom Owen. Is he really a "forensics expert?"
Well, no. He has a B.A. in History, not forensics.
Well, surely since he's an expert, he went to Harvard or Yale or Oxford, right?
Well, no he went to Bellarmine College in Kentucky. You've heard of Bellarmine College, right? [Normally I deplore this credentialism but if Tom Owen was an expert for the right his college degree is all we would hear about.]
Well, but surely he's worked for the FBI or CIA as a forensics examiner?
No, but he did work for the New York Public Library in charge of their Rogers and Hammerstein archive.
But surely he's written some books about forensics that the FBI and CIA use, right?
No, but he has written extensively about the banjo and did a coloring book:
Tom Owen, Scaling the Fretboard (Chappell Music 1973)
Tom Owen, The Chord Coloring Book (Chappell Music 1974)
Tom Owen, Tenor Banjo (Chappell Music 1975)
Tom Owen, Lead Guitar (Chappell Music 1976)
Tom Owen, The Classic Blues Singers (Chappell Music 1977)
What about his wife Jennifer Owen ... surely she's a hotshot FBI forensics examiner, right?
No, she makes Powerpoint presentations and is a secretary with a political science degree, not a forensics degree.
But surely they have an advanced forensic acoustics laboratory where they conduct their forensic analysis right?
No, they just have a computer in the basement of their house in New Jersey right next to the railroad tracks.
But surely he's a member of the American Board of Recorded Evidence?
Yes, but he and his wife run the Board. He's the chairman, and she's a board member. The Board is run out of a weight-loss clinic in Springfield, Missouri along with a bunch of other dubious "boards," "colleges" and "Institutes."
American Board for Certification in Homeland Security - Address: 2750 East Sunshine St. Springfield, MO
American Association for Integrative Medicine Inc - Address: 2750 East Sunshine St. Springfield, MO
American College of Forensic Examiners International - Address: 2750 East Sunshine St. Springfield, MOC
College of Wellness - Address: 2750 East Sunshine St. Springfield, MO
American Psychotherapy Association - Address: 2750 East Sunshine St. Springfield, MO
There are no colleges or real boards here. There's a fat farm weight loss clinic at that location. They appear to have certified themselves experts by running this board themselves.
Now, let's examine the software they used to perform their analysis. How good is it?
Well, given two KNOWN samples of speech by President Richard M. Nixon, the software only matched two recordings to a 86% match.
Remember, Mr. Owen said he'd expect a 90% match before he concluded that the voices were identical. Although when he's testifying in murder cases, he claims a 68% match is enough to send someone to prison for the rest of their life (CT v Sheila Davalloo). Even in the software makers own demonstration of the product, using two KNOWN samples of speech from the same famous person, there was only an 86% match.
What about the algorithm they're using to make the comparison? How good is it? UNKNOWN. That's proprietary. They won't tell you what they're actually measuring.
I am leaving that up there for folks to check over (and it was left on April 1), but if it is even mostly right, this guy won't be taking the stand in The People versus Zimmerman.
I did note yesterday that Mr. Owen is rolling out their new product as of March 1, 2012, so he welcomes the publicity.