speak (Unix)

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. It was first included in Unix v3 and possibly later ones, with the OS-end support files and help files persisting until v6 and some but not all versions of 7. Neither the original binaries nor the source code for speak have been found yet, though at least three versions of the man page are known to still exist.

The main program (speak) was around 4500 bytes, the rule tables (/etc/speak.m) were around 11000 bytes, and the table viewer (speakm) was around 1900 bytes.

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 was included with the 1st Edition of Unix in 1973. In 1974, Douglas McIlroy published a paper describing the workings of this algorithm. It is quite likely that this algorithm, later referred to as the "Mcilroy Algorithm", provided the inspiration for a later (1976), simpler text-to-speech algorithm developed jointly by Votrax and the U.S. Naval Research Laboratory, known as the "NRL Algorithm".

According to the McIlroy paper, "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.