Voice analysis for the KGB? 

That's what political prisoners with special skills are forced to do in Alexander Solzhenitsyn's fact-based novel, The First Circle.  Although imprisoned, these scientists have a unique position in Stalin's Russia.  They live in a penal institution that doubles as a scientific research center and their assignment is to develop voiceprint technology.  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.  Acoustic scientists used it during World War II, as seen in Solzhenitsyn's novel, to attempt to identify enemy voices on telephones and radios.  However, with the war's end, the urgency for this technology diminished and little came of it until later.

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.  He was a physicist who had worked with the sound spectrograph in its early days.  It took him more than two 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 had even brought in professional mimics to try to fool the machine, but try as they might to imitate someone else's voice, the mimics showed up in the graph as quite dissimilar from the original voices.  Kersta eventually broke away from Bell Laboratories to market the machine on his own.

Then in 1966, the Michigan State Police started to work on a practical application of voiceprint technology in criminal investigations.  They formed a Voice Identification Unit and hired Kersta to train these officers.  Their intent was to use it to assist with ongoing cases, but it wasn't long before its legal weight was reviewed in a courtroom.

Voiceprint technology came into the American courts in the 1960s, and judges were divided on whether or not to admit it as scientific evidence.  There was little research to support it, there were few people who really could be called technical experts, and linguists testified against one another on its viability.  

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.  First, Let's look at how the sound spectrograph worked in a murder investigation.