In more than 40 years at IBM Research and Johns Hopkins, Jelinek led the way in developing the statistical theory behind modern voice-recognition systems. Essentially, he helped turn a nascent science that merely transcribed human speech into a sophisticated one that could interpret meaning and anticipate what the speaker would say next.
"He envisioned applying the mathematics of probability to the problem of processing speech and language," said Sanjeev Khudanpur, associate professor of electrical engineering at Johns Hopkins. "This revolutionized the field. Fifty years ago no one thought that was possible. Today, it's the dominant paradigm."
Born Nov. 18, 1932, to a Jewish father and Christian mother in Kladno in what is now the Czech Republic, Jelinek was barred from formal schooling by Nazi edict after he finished the second grade. Through much of World War II, he was educated in underground academies.
The family moved to Prague after being ousted from their home by Nazi occupiers, said Jelinek's son William. Jelinek's father died of disease in the concentration camp at Terezin shortly after the Allied liberation.
In 1949, the family moved to the United States. He earned a bachelor's degree at the Massachusetts Institute of Technology in 1956. He stayed on at MIT to earn a master's degree in 1958 and a doctorate in 1962.
William Jelinek said his father traveled in 1957 to a professional conference in what was then Czechoslovakia, where he met and fell in love with Milena Tobolova, a filmmaker and dissident against the Communist government.
For years after that, Tobolova was barred from leaving the country, her son said. But during a visit by Soviet leader Nikita Khrushchev to the United States, Jelinek's academic adviser Jerome Wiesner, who was also a science aide to then-Sen. John F. Kennedy, asked Khrushchev to intervene with Czech authorities. Soon after Kennedy was elected president, Tobolova was allowed to emigrate.
"As an inaugural gift to Kennedy, the Czechs released nine dissidents and one of them was my mother," William Jelinek said. The couple married in 1961.
While at MIT, Frederick Jelinek became interested in applying information theory to linguistics. After receiving his doctorate, he accepted an offer to teach and study information theory at Cornell University.
In 1972, Jelinek accepted a summer position at IBM Research, which was just beginning to work on speech recognition. Eventually, he said, he was forced to decide between Cornell and his expanding role in IBM Research. He chose IBM, where he worked for 21 years and headed a team that sought to apply the power of supercomputers to the challenges of transcribing and translating the spoken word.
Khudanpur said that previous efforts at voice recognition and translation focused on codifying rules and applying them — an approach that was frustrated by the complexity and subtlety of language. Jelinek's approach was to assemble a huge database of text and let the computer calculate the probabilities of words appearing in relation to other words — deriving meaning from context rather than rules.
The strategy was widely questioned at the time, but when the Defense Advanced Research Projects Agency sponsored a competition in the field in 1980, Khudanpur said, Jelinek's approach prevailed.
"By the '90s, everybody was on board," Khudanpur said.
Jason Eisner, associate professor of computer science at Johns Hopkins, called Jelinek's application of statistical theory and probability to voice recognition a trailblazing approach that later was adapted to many other fields that employ artificial intelligence, including stock market prediction and biomedical research.
Jelinek retired from IBM in 1993 and was recruited by Johns Hopkins to head its Center for Language and Speech Processing.
Among his many professional awards, he was inducted into the National Academy of Engineering in 2006.
In addition to his son, of Briarcliff Manor, N.Y., and his wife, of New York, Jelinek is survived by a daughter, Hannah Sarbin of Larchmont, N.Y., a sister, Susan Abramowitz of Montreal, and three grandchildren.