Editing Speech synthesis (section)

=== Formant synthesis ===

[[Formant]] synthesis does not use human speech samples at runtime. Instead, the synthesized speech output is created using [[additive synthesis]] and an acoustic model ([[physical modelling synthesis]]).<ref>Dartmouth College: [http://digitalmusics.dartmouth.edu/~book/MATCpages/chap.4/4.4.formant_synth.html ''Music and Computers''] {{webarchive|url=https://web.archive.org/web/20110608035309/http://digitalmusics.dartmouth.edu/~book/MATCpages/chap.4/4.4.formant_synth.html |date=2011-06-08 }}, 1993.</ref> Parameters such as [[fundamental frequency]], [[phonation|voicing]], and [[noise]] levels are varied over time to create a [[waveform]] of artificial speech. This method is sometimes called ''rules-based synthesis''; however, many concatenative systems also have rules-based components.
Many systems based on formant synthesis technology generate artificial, robotic-sounding speech that would never be mistaken for human speech. However, maximum naturalness is not always the goal of a speech synthesis system, and formant synthesis systems have advantages over concatenative systems. Formant-synthesized speech can be reliably intelligible, even at very high speeds, avoiding the acoustic glitches that commonly plague concatenative systems. High-speed synthesized speech is used by the visually impaired to quickly navigate computers using a [[screen reader]]. Formant synthesizers are usually smaller programs than concatenative systems because they do not have a database of speech samples. They can therefore be used in [[embedded system]]s, where [[data storage device|memory]] and [[microprocessor]] power are especially limited. Because formant-based systems have complete control of all aspects of the output speech, a wide variety of prosodies and [[intonation (linguistics)|intonation]]s can be output, conveying not just questions and statements, but a variety of emotions and tones of voice.

Examples of non-real-time but highly accurate intonation control in formant synthesis include the work done in the late 1970s for the [[Texas Instruments]] toy [[Speak & Spell (game)|Speak & Spell]], and in the early 1980s [[Sega]] [[Video arcade|arcade]] machines<ref>Examples include [[Astro Blaster]], [[Space Fury]], and [[Star Trek (arcade game)|Star Trek: Strategic Operations Simulator]]</ref> and in many [[Atari, Inc.]] arcade games<ref>Examples include [[Star Wars (arcade game)|Star Wars]], [[Firefox (arcade game)|Firefox]], [[Star Wars: Return of the Jedi (arcade game)|Return of the Jedi]], [[Road Runner (video game)|Road Runner]], [[Star Wars: The Empire Strikes Back (arcade game)|The Empire Strikes Back]], [[Indiana Jones and the Temple of Doom (arcade game)|Indiana Jones and the Temple of Doom]], [[720°]], [[Gauntlet (arcade game)|Gauntlet]], [[Gauntlet II]], [[A.P.B. (video game)|A.P.B.]], [[Paperboy (video game)|Paperboy]], [[RoadBlasters]],  [http://www.arcade-museum.com/game_detail.php?game_id=10319 Vindicators Part II], [[Escape from the Planet of the Robot Monsters]].</ref> using the [[Texas Instruments LPC Speech Chips|TMS5220 LPC Chips]]. Creating proper intonation for these projects was painstaking, and the results have yet to be matched by real-time text-to-speech interfaces.<ref>{{Cite book |author=John Holmes and Wendy Holmes |title=Speech Synthesis and Recognition |edition=2nd |publisher=CRC |year=2001 |isbn=978-0-7484-0856-6}}</ref>{{When|date=April 2025}}