Vintage Speech Synthesizer Croons The Oldies

If you listened to the National Weather Service Weather Radio in the US about 25 years ago, you’ll no doubt remember [Perfect Paul], one of the synthesized voices used to read current conditions and weather forecasts. The voice came from a DECtalk DTC01, a not inexpensive voice synthesizer first made in 1984 that also gave voice to [Stephen Hawking] for many years.

Long obsolete, the DECtalk boxes have a devoted following with hobbyists who like to stretch what the device can do. Some even like to make it sing, after a fashion, and [Michael] decided that making a DECtalk sing “Xanadu”, the theme song from the 1980 [Olivia Newton-John] musical extravaganza, was a good idea. Whether it actually was is debatable, and we’ll take exception with having that particular ditty stuck in our head as a result, but we don’t judge except on the merits of the hack.

It’s actually easy if you have a DECtalk; the song is a straight ASCII file with remarkably concise instructions on which phonemes the box needs to generate. Along with inflection, tone, and timing instructions, the text file looks almost completely unlike English while still somehow being readable. The DECtalk accepts the file over RS-232, which would be easy enough to do with a modern computer, but [Michael] upped his game a bit by using a TRS-80 Model 100 computer as a serial terminal. The synthesized song is in the video below, with the original included for reference by those who didn’t experience endure the late disco-era glory days.

DECtalks seem pretty rare in the wild, so we appreciate this glimpse at what they can do. There are other retro speech synthesizer hacks, though: the simulated walnut goodness of the Votrax and the MicroVox come to mind, as does the venerable TI Speak and Spell.

33 thoughts on “Vintage Speech Synthesizer Croons The Oldies

      1. The later part of Xanadu was much better, sounded more like singing than the early part.
        I used to have a TI-99/4A with speech synthesizer, had fun getting it to say words that were outside its conventional english phoneme set. Getting an intelligible “Taj Mahal” out of it took a lot of work.

    1. Yes I have used the emic 2 as well but switched to the text to speech mikrobus module from Mikroelektronika. Same Epson chip. And already uses dectalk v5. Many of the songs do not work with v5 though and require hand editing. Hence dectalk v2 is better for singing ;-)

  1. The problem with the DCT01 was that it had the switch on the front. I would often find the one I had connected to the network monitoring system turned off as it was “irritating”.

    1. No EDIT? Nice… So anyway, see: It does “Industry-standard DECtalk text-to-speech synthesizer engine (5.0.E1)” I will try some of the ‘songs’ with mine, which is part of my home automation system, driven by an Arduino MEGA. Sound output is great; cheap, goes around corners, easy to wire to other rooms. And with unobtrusive Morse Code buttons, I can lie in bed in the dark with my eyes closed, find the button and control the system.

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  2. My dear hacker fellows, thanks a lot for all the requests, but I’ll need some time to set it up again. I’ll post them on YouTube in a week or so, please stay tuned! Cheers Michael

  3. FWIW, I used the DECTalk on a device I created for voice-challenged folks back in the mid ’80s It’s called a DynaVox, by Sentient Systems (later to be known as DynaVox Inc.). If you can find one, it contains a TMS320 DSP for the vocal tract model, and a 68000 for the text to phoneme work. There is a secret back door to allow full access to all the hidden DECTalk features, such as singing, high-hat to make the classic millennial-speak hi-hat at the end of every sentence that makes everything sound like questions. This is all accessible via the RS-232 port. All the voices are in there too. I loved it when the kids all personalized their voices to me some flavor of Huge Harry.

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