PlainTalk is the collective name for several speech synthesis (MacInTalk) and speech recognition technologies developed by Apple Inc.
In 1990, Apple invested a lot of work and money in speech recognition technology, hiring many respected researchers in the field. The result was "PlainTalk", released with the AV Quadras of 1993. It was made a standard system component in System 7.1.2, and has since been shipped on all PowerPC and even some 68K Macintoshes.
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Apple's text-to-speech uses diphones. Compared to other methods of synthesizing speech, it is not very resource-intensive, but there is a limit to how natural the synthesis can get. See the speech synthesis article for details. American English and Spanish versions have been available, but since the advent of Mac OS X, Apple has shipped only American English voices, relying on third-party suppliers such as Acapela Group to supply voices for other languages.
An application programming interface known as the Speech Manager enables third-party developers to use speech synthesis in their applications. There are various control sequences that can be used to fine-tune the intonation and rhythm. The volume, pitch and rate of the speech can be configured as well.
Input to the synthesiser can be controlled explicitly using a special phoneme alphabet.
The initial Macintosh text-to-speech engine, MacinTalk (named by Denise Chandler), was used by Apple in the 1984 introduction of the Macintosh in which the computer announced itself to the world. While it was incorporated into the Macintosh's operating system, it was not officially supported by Apple (though programming information was made available through an Apple Technical Note). MacinTalk was developed by Joseph Katz and Mark Barton who later founded SoftVoice, Inc. which currently markets TTS engines for Windows, Linux and embedded platforms.
Eventually, Apple released a supported speech synthesis system, called MacInTalk 2. It supports any Macintosh running System Software 6.0.7 or later. It remained the recommended version for slower machines even after the release of MacInTalk 3 and Pro.
MacinTalk 3 introduced a great variety of voices. Apart from the standard adult voices 'Ralph', 'Fred' and 'Kathy', and children's voices like 'Princess' and 'Junior', various novelty voices were included, like 'Whisper', 'Zarvox' (a robot voice with melodic background sounds, with a similar voice called 'Trinoids' also included), 'Cellos' (a voice that sung its text to an Edvard Grieg tune, with similarly-singing voices like 'Good News', 'Bad News', 'Pipe Organ'), 'Albert' (a hoarse-sounding voice), 'Bells', 'Boing', 'Bubbles' etc.
Each of these voices came with its own example text, that would be spoken when one hit the 'Test' button in the Speech control panel. Some would just say their name, language and the version of MacinTalk they were introduced with. Others would say funny things, like 'I sure like being inside this fancy computer', 'I have a frog in my throat... No, I mean a real frog!', or 'The light you see at the end of the tunnel is the headlamp of a fast approaching train'. These voices as well as their test texts are still in Mac OS X today.
With the increase in computer power that the CPUs in AV Macs and PowerPC based Macintoshes provided, Apple could afford to increase the quality of the synthesis. MacInTalk 3 required a 33 MHz 68030 processor and MacInTalk Pro required a 68040 or better and at least 1 MB of RAM. Each synthesizer supported a different set of voices.
Text-to-speech has been a part of every Mac OS X version. The Victoria voice was enhanced significantly in Mac OS X v10.3, and added as Vicki (Victoria was not removed). Its size was almost 20 times greater, because of the higher-quality diphone samples used. (sample)
A new, much more natural-sounding voice, called "Alex" has been added to the Mac text-to-speech roster with the release of Mac OS X 10.5 Leopard.[1]
With Mac OS X 10.7 Lion, voices are available in additional U.S. English and other English accents, as well as 21 other languages. [2]
Apple hired many speech recognition researchers in 1990. After about a year, they demonstrated a technology codenamed Casper. It was released as part of the PlainTalk package in 1993. Although available for all PowerPC Macintoshes and AV 68k machines (it was one of the few applications that made use of the DSP in the Centris 660AV and Quadra 840AV), it was not part of the default system install prior to Mac OS X. The user had to do a custom installation of the OS to get speech recognition capabilities.
Apple's speech recognition is voice-command oriented, i.e. not intended for dictation. It can be configured to listen for commands when a hot key is pressed, after being addressed with an activation phrase such as "Computer", or "Macintosh", or without prompt. A graphical status monitor, often in the form of an animated character, provides visual and textual feedback about listening status, available commands and actions taken. It can also communicate back with the user using speech synthesis.
Early versions of the speech recognition provided full access to the menus. This support was later removed, since it required too many resources and made recognition less reliable, only to be re-added in Mac OS X 10.3 as a "universal access technology" called spoken user interface.
The user can launch items located in a special folder, called "Speakable Items", simply by speaking their name (while the system is in listening mode). Apple shipped a number of AppleScripts in this folder, but aliases, documents and folders can be opened in the same way.
Additional functionality is provided by individual applications. An application programming interface lets programs define and modify an available vocabulary. For example, the Finder provides a vocabulary for manipulating files and windows.
The MacinTalk speech synthesis can be heard in a few songs:
MacInTalk's 'Ralph' voice serves as the voice of the computerized autopilot, "Auto", in the 2008 DisneyยทPixar film WALL-E. "MacInTalk" is credited as the voice of Auto in the film's end credits.
MacinTalk was used to perform the part of the wheelchair-using motor neurone disease patient with a voice synthesizer in the animated Family Guy episode "Ready, Willing and Disabled", who would later appear again in "Brian the Bachelor" and "Brian Goes Back To College". It was furthermore used in "Peterotica", when Stewie plays with "the speech function on his Macintosh", Using Talking Moose software, Stewie gets his laptop to say "Stewie is cool." & also in "April in Quahog" where MacinTalk Fred voices Stephen Hawking. It was also used to introduce episodes on the anime Serial Experiments Lain. Also in the Transformers Animated Feature length episode Transwarped, the Autobot Perceptor's voice actor was credited as plaintalk. It was also used in the short-lived cartoon Whatever Happened to Robot Jones? as the voice of Robot Jones' father, Dad Unit, and Robot in the first season. It was also used as the voice for the Red vs. Blue character, the lying A.I Gary/Gamma. Junior was voicing Robot Jones in the 2000 episode of The Cartoon Cartoon Show, Whatever Happened to... Robot Jones?. All Macintalk voices will voice the crazy & evil computers, & it will be heard in the upcoming episode of The Problem Solverz, "Macintosh Mayhem." An episode where All Macintosh computers go crazy & evil & take over the world. Roba will be voiced by Macintalk Fred in the upcoming tv show, "Neon Knome." Macintalk Junior will voice Bobert in season 2 of The Amazing World of Gumball, but Junior will also dub Bobert in the season 1 episodes.
Apple produced a microphone called "Apple PlainTalk Microphone". It was introduced alongside the AV-enabled Quadras in 1993 but was also sold separately. It had a longer connector, and the tip was used to provide it with extra power. It was designed to be positioned on top of the screen and to be sensitive to sound from the front.