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Dennis H. Klatt (1938–1988)
Text-to-speech (TTS) systems are computers that read typewritten text and then speak it out loud. The first English text-to-speech system originated in Japan in 1968. But it was DECtalk, a standalone appliance for turning text to speech, that commoditized this technology. The invention helped many people, including those unable to talk due to medical reasons or disabilities. While a lot of basic research fails to transition into practical applications, DECtalk was a success story.
Much of DECtalk’s core capability was built on the text-to-speech algorithms developed by Dennis Klatt, who had joined MIT as an assistant professor in 1965. Packaged into a hardware appliance by the Digital Equipment Corporation, DECtalk had asynchronous serial ports that could connect to virtually any computer with an RS-232 interface. DECtalk was kind of like a printer, but for voice! Two telephone jacks let users hook DECtalk up to a telephone line, allowing DECtalk to make and receive calls, speak to the person at the other end of the phone line, and decode the touch tones of their responses.
TTS systems such as DECtalk work by first converting text to phonemic symbols and then converting the phonemic symbols to analog waveforms that can be heard by humans as sound.
When it launched, DECtalk’s price tag was approximately $4,000, and it came equipped with a variety of different speaking voices. Over time, the number of voices expanded, with names such as Perfect Paul, Beautiful Betty, Huge Harry, Frail Frank, Kit the Kid, Rough Rita, Uppity Ursula, Doctor Dennis, and Whispering Windy. An early user of the DECtalk algorithm is the world-famous British physicist Stephen Hawking, who lived with amyotrophic lateral sclerosis, or ALS. Unable to talk, his voice is best recognized as “Perfect Paul.” The National Weather Service also used DECtalk for its NOAA Weather Radio broadcasts.
SEE ALSO Electronic Speech Synthesis (1928)
After he was unable to speak because of the progress of a degenerative nerve disease, physicist Stephen Hawking used a text-to-speech device as his voice.