speak was a Unix utility that used a predefined set of rules to turn a file of English text into phoneme data compatible with a Federal Screw Works (later Votrax) model VS4 "Votrax" Speech Synthesizer.^[1][2] It was first included in Unix v3^[3] and possibly later ones, with the OS-end support files and help files persisting until v6. As of late 2011, the original source code^[4][5] for speak, and portions of speak.m (which is generated from speak.v)^[6] were discovered. At least three^[7][8][9] versions of the man page are known to still exist.

The main program (speak) was around 4500 bytes,^[1] the rule tables (/etc/speak.m) were around 11,000 bytes,^[1] and the table viewer (speakm)^[10] was around 1900 bytes.^[1]

History

The speak utility was developed by Douglas McIlroy in the early 1970s at AT&T Bell Labs in Murray Hill, New Jersey. It was included with the 1st Edition of Unix in 1973. In 1974, McIlroy published a paper describing the workings of this algorithm.^[1]

According to the McIlroy paper,^[1] "K. Thompson and D. M. Ritchie integrated the device smoothly into the operating system", which is evident from /usr/sys/dev/vs.c "Screw Works Interface via DC-11".

McIlroy Algorithm

The McIlroy Algorithm is a large set of rules, sub-rules, and sub-sub-rules, applied to a word to isolate long vowels, silent 'e's, and slowly convert each letter into its "Screw Works" equivalent phoneme code.^[11] The intention of the algorithm is to convert any English text into Votrax Phoneme codes, which could be played back/recited by a Federal Screw Works "Votrax" speech synthesizer.

A later (1976), simpler text-to-speech algorithm developed jointly by Votrax and the U.S. Naval Research Laboratory, known as the "NRL Algorithm", serves a similar purpose.

References