Back in the early 1980s, there was a certain fad in making your computer produce something resembling human speech. There were several hardware solutions to this, adding voices to everything from automated telephone systems to video game consoles, all the way to Steve Jobs using the gimmick to introduce Macintosh to the world in 1984. In 1982, a software-based version of this synthesis was released for the Atari 8-bit line of computers, and ever since them [rossumur] has wondered whether or not it could run on the very constrained 2600.

Fast-forward 38 years and he found out that the answer was that yes, it was indeed possible to port a semblance of the original 1982 Software Automatic Mouth (or SAM) to run entirely on the Atari 2600, without any additional hardware. To be able to fit such a seemingly complicated piece of software into the paltry 128 bytes (yes, bytes) of RAM, [rossumur] actually uses an authoring tool in order to pre-calculate the allophones, and store only those in the ROM. This way, the 2600 alone can’t convert text to phonemes, but there’s enough space left for the allophones, which are converted into sound, that about two minutes of speech can fit into one cartridge. As for why he went through the trouble, we quote the author himself: “Because creating digital swears with 1982 speech synthesis technology on a 1977 game console is exactly what we need right now.”

For this project, [rossumur] has written an incredibly interesting article on speech synthesis in order to explain the SAM engine used here. And this isn’t his first time on the website either, always cramming software where it shouldn’t fit, such as a “Netflix”-like streaming service, or 8-bit console emulators, both on nothing but an ESP32 microcontroller. Check this one out in action after the break.

This is the under-the-hood view of the keyboard for the Voder (Voice Operating Demonstrator), the first electronic device capable of generating continuous human speech. It accomplishes this feat through a series of keys that generate the syllables, plosives, and affricatives normally produced by the human larynx and shaped by the throat and tongue. This week’s film is a picture montage paired with the audio from the demonstration of the Voder at the 1939 World’s Fair.

The Voder was created by one [Homer Dudley] at Bell Laboratories. He did so in conjunction with the Vocoder, which analyzes human-generated speech for encrypted transfer and re-synthesizes it on the other end. [Dudley] spent over 40 years researching speech at Bell Laboratories. His development of both the Voder and the Vocoder were instrumental in the SIGSALY project which aimed to deliver encrypted voice communication to the theatres of WWII.

In this film, the Voder is first demonstrated with a flat, robotic rendition of the phrase “she saw me”. The operator then runs through the various possible inflections to show the flavor that the foot pedal provides. Inside the Voder is a group of band pass filters in parallel that span the frequency range of human speech. Excitations are received from either the noise generator or the relaxation oscillator, and selection between the two is made from the wrist bar. The pitch is controlled with the foot pedal. The band pass outputs are fed to ten gain pots under the operators fingers. Three additional keys manipulate the excitations to produce the consonant stop sounds like /t/, /d/, /p/, /b/, /k/, and /g/.

Voder’s pitch can be adjusted to emulate all kinds of voices, from man to woman to child. It is capable of speaking an any language the operator can speak. As a special bonus, Voder makes very convincing cow and pig sounds.

In creating the Voder, it was discovered that non-inflected vowels sounded like a foghorn, so vibrato was added to make them more human. This of course means that Voder can sing, and the operator gives a heartwarming performance of “Auld Lang Syne”.

For an operator, getting the Voder to speak is a difficult undertaking. Generating a single word requires the keying of several sounds in quick succession, along with simultaneous wrist bar action and pedal work to color the inflection. Bell Labs auditioned a few hundred girls to train in Voder operation, but ultimately had fewer than 30 expert operators. [Helen Harper], who you hear in this film, was considered the best. According to [Helen], mastery required about a year of constant practice.

[Thanks to Fran for the tip!]

[Voder keyboard image source]