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Voiceprint Analysis Unit

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Olivia Hayhoe

on 27 May 2011

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Transcript of Voiceprint Analysis Unit

Voiceprint Analysis Unit Olivia Hayhoe & Sara Manyen Voiceprint- A pictorial representation of the frequency, duration and amplitude of human voice sounds this unit is involved in cases with telephoned threats or tape-recorded messages combination of both aural (listening) and spectrographic (instrumental) comparison of one or more known voices with an unknown voice for the purpose of identification or elimination the sound spectograph is an instrument that converts speech into a visual graphic display, called a spectogram. developed at Bell Telephone Laboratories in 1941 During World War II, it was used for military intelligence purposes use in forensic investgation dates back to the 1960's Bell System engineer, Lawrence Kersta, became convinced that voiceprints could provide a valuable means of personal identification took him more than 2 years and the analysis of over 50,000 voices, but he managed to offer a technique that he claimed tested at 99.65% accuracy he contended that each voice has its own unique quality and character depends on:
vocal cavaties (throat, nasal and 2 oral cavaties formed by the positioning of the tongue)
Articulators (lips, teeth, tongue, soft palate and jaw muscles) From 1967 until the present, more than 5,000 law enforcement related voice identification cases have been processed by certified voiceprint examiners However, there are still conflicting opinions whether this can be used as scientific evidence due to Frye Standard (general acceptance) spectograms are placed side by side for comparison
they can then classify the recording into one of the seven categories as recomended by the American Board of Recorded Evidence: 1. a positive identification with more than 20 matching speech sounds
2. a probable identification with more than 15 matching sounds and no unexplained differences
3. a possible identification with more than 10 matching sounds and no unexplained differences
4. an inconclusive decision mainly due to a poor recording
5. a possible elimination with 10 or more sounds that do not match
6. a probable elimination with 15 or more sounds that do not match
7. a positive elimination with 20 or more sounds that do not match Case of Clifford Irving occured in 1971
he made a book deal and was paid a large amount of money in advance
he claimed that Howard R. Hughes, a billionaire, had authorized him to write a biography
Voiceprint comparisions were made between the alleged phone call tape and a speech Hughes made
The two did not match up, Irving was charged with fraud and sentenced to 30 months in prison People vs Kelly Robert Emmett Kelly, convicted of extortion by the Supreme Court
extortion arose from several anonymous and threatening phone calls to Terry Waskin
The taped calls were sent to be analyzed by a technician at Michigan State Police Office
The tests confirmed that the voice was Kelly's and that they could be used against him in court
Kelly was convicted
But, the judgement was reversed because the voiceprint was not "up to Frye Standards" The Voiceprint of a Killer 1971
Body found dead in woods
body burried with several bullets
head burried with several bullets also
all the men who had been convicted of hunting illegally on the grounds were called in for questioning and polygraph tests
one man, Brian Hussong, refused to co-operate
he had no alibi and was a likely suspect so the investigators wired his house and recorded all his phone messages
Hussong was recorded talking to his grandmother about hiding his guns and figuring out an alibi
the tapes were sent to Michigan's Voice Identification Unit
the tapes and voice sample were matched
Hussong was found guilty of first degree murder and was sentenced to a life in prison Sources Forensics book
http://expertpages.com/news/voiceprint_identification.htm
http://www.enotes.com/forensic-science/voice-analysis
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