05-09-2005

http://www.crimelibrary.com/criminal_mind/forensics/voiceprints/1.html
The Origin of Voiceprints
By Katherine Ramsland
Voice analysis for the KGB?
This article is about Alexander Solzhenitsyn's fact-based novel, The First Circle, in Stalin’s Russia. While the Russian secret police analyze phone calls in Germany, the technicians are pressed to figure out how to scientifically measure the individuality of the human voice. The novel offers a fascinating glimpse into the early days of this technology, but it was not in 1949 Russia where it all began. The idea that someone could be identified by the sound of his voice had its origins in the work of Alexander Melville Bell (father to Alexander Graham Bell). Over one hundred years ago, he developed a visual representation of what the spoken word would look like. It was based on pronunciation and he showed that there were subtle differences among different people who said the same things. His son later joined him in using the system to help deaf people to speak. Then in 1941, the laboratories of Bell Telephone in New Jersey produced a machine—the sound spectrograph—for mapping a voice onto a graph. It analyzed sound waves and produced a visual record of voice patterns that were based on frequency, intensity, and time.
Voiceprint technology began to get notice for criminal investigations in the early 1960s when the New York City Police Department received numerous bomb threats by phone against major airlines. Stymied, the FBI asked Bell Labs to help. Lawrence G. Kersta, one of their senior engineers, was assigned the task of figuring out a method of identification that would stop the calls and bring the perpetrators to justice. The first case was in military court, United States v. Wright, and that began the judicial controversy. One court ruled the technology admissible, but a dissenting judge wrote a detailed opinion on why it should not be considered scientifically acceptable. The New Jersey Supreme Court was the first non-military court to make an appellate review, in State v. Cary. Courts in New York and California had admitted this type of testimony, so the New Jersey justices remanded the case to check the accuracy of the equipment. Another appeal came their way and they ruled that it was too early to tell whether this method was reliable. After several more times back and forth, with no new scientific support, the voiceprint identification evidence was excluded. The reason for this, and the subsequent case history, are supplied in detail in Section Five.
The author wrote this article because those who do the recordings for analysis must also be competent to operate the recording device, because the quality of the tape has great bearing on the interpreter's results.
The skills involved in aural and visual voice interpretation include:
Critical listening, with an ear for anomalies and the ability to audit foreground information as distinguishable from background
Ability to check for tape tampering
Experience reading magnetic tapes
Ability to operate the spectrograph equipment, both for general results and for zooming in on specific patterns
Ability to work with an investigative team
In all likelihood, voiceprints will continue to play a key role in any investigation that involves voice evidence. As such, they will become part of the evidence brought into court. Like other technologies that once were resisted but are now fully admissible, voiceprints may soon have their day.