The Info List - Speech Synthesis

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SPEECH SYNTHESIS is the artificial production of human speech . A computer system used for this purpose is called a SPEECH COMPUTER or SPEECH SYNTHESIZER, and can be implemented in software or hardware products. A TEXT-TO-SPEECH (TTS) system converts normal language text into speech; other systems render symbolic linguistic representations like phonetic transcriptions into speech.

Synthesized speech can be created by concatenating pieces of recorded speech that are stored in a database . Systems differ in the size of the stored speech units; a system that stores phones or diphones provides the largest output range, but may lack clarity. For specific usage domains, the storage of entire words or sentences allows for high-quality output. Alternatively, a synthesizer can incorporate a model of the vocal tract and other human voice characteristics to create a completely "synthetic" voice output.

The quality of a speech synthesizer is judged by its similarity to the human voice and by its ability to be understood clearly. An intelligible text-to-speech program allows people with visual impairments or reading disabilities to listen to written words on a home computer. Many computer operating systems have included speech synthesizers since the early 1990s. Overview of a typical TTS system

Automatic announcement

A synthetic voice announcing an arriving train in Sweden
. -------------------------

Problems playing this file? See media help .

Sample of Microsoft Sam Microsoft Windows XP 's default speech synthesizer voice saying "The quick brown fox jumps over the lazy dog 1,234,567,890 times". It is then followed by a demonstration of a glitch that occurs when the words "SOI/SOY" are entered -------------------------

Problems playing this file? See media help .

A text-to-speech system (or "engine") is composed of two parts: a front-end and a back-end . The front-end has two major tasks. First, it converts raw text containing symbols like numbers and abbreviations into the equivalent of written-out words. This process is often called text normalization, pre-processing, or tokenization . The front-end then assigns phonetic transcriptions to each word, and divides and marks the text into prosodic units , like phrases , clauses , and sentences . The process of assigning phonetic transcriptions to words is called text-to-phoneme or grapheme -to-phoneme conversion. Phonetic transcriptions and prosody information together make up the symbolic linguistic representation that is output by the front-end. The back-end—often referred to as the synthesizer—then converts the symbolic linguistic representation into sound. In certain systems, this part includes the computation of the target prosody (pitch contour, phoneme durations), which is then imposed on the output speech.


* 1 History

* 1.1 Electronic devices

* 2 Synthesizer

* 2.1 Concatenation synthesis

* 2.1.1 Unit selection synthesis * 2.1.2 Diphone synthesis * 2.1.3 Domain-specific synthesis

* 2.2 Formant synthesis * 2.3 Articulatory synthesis * 2.4 HMM-based synthesis * 2.5 Sinewave synthesis

* 3 Challenges

* 3.1 Text normalization challenges * 3.2 Text-to-phoneme challenges * 3.3 Evaluation challenges * 3.4 Prosodics and emotional content

* 4 Dedicated hardware

* 5 Hardware and software systems

* 5.1 Mattel
* 5.2 SAM * 5.3 Atari * 5.4 Apple * 5.5 AmigaOS * 5.6 Microsoft Windows * 5.7 Texas Instruments TI-99/4A

* 6 Text-to-speech systems

* 6.1 Android * 6.2 Internet * 6.3 Open source * 6.4 Others * 6.5 Digital sound-alikes

* 7 Speech
synthesis markup languages * 8 Applications * 9 APIs * 10 See also * 11 References * 12 External links


Long before the invention of electronic signal processing , some people tried to build machines to emulate human speech. Some early legends of the existence of "Brazen Heads " involved Pope Silvester II (d. 1003 AD), Albertus Magnus (1198–1280), and Roger Bacon (1214–1294).

In 1779 the Danish scientist Christian Gottlieb Kratzenstein won the first prize in a competition announced by the Russian Imperial Academy of Sciences and Arts for models he built of the human vocal tract that could produce the five long vowel sounds (in International Phonetic Alphabet notation: , , , and ). There followed the bellows -operated "acoustic-mechanical speech machine " of Wolfgang von Kempelen of Pressburg , Hungary
, described in a 1791 paper. This machine added models of the tongue and lips, enabling it to produce consonants as well as vowels. In 1837, Charles Wheatstone
Charles Wheatstone
produced a "speaking machine" based on von Kempelen's design, and in 1846, Joseph Faber exhibited the "Euphonia ". In 1923 Paget resurrected Wheatstone's design.

In the 1930s Bell Labs developed the vocoder , which automatically analyzed speech into its fundamental tones and resonances. From his work on the vocoder, Homer Dudley developed a keyboard-operated voice-synthesizer called The Voder (Voice Demonstrator), which he exhibited at the 1939 New York World\'s Fair .

Dr. Franklin S. Cooper and his colleagues at Haskins Laboratories built the Pattern playback in the late 1940s and completed it in 1950. There were several different versions of this hardware device; only one currently survives. The machine converts pictures of the acoustic patterns of speech in the form of a spectrogram back into sound. Using this device, Alvin Liberman and colleagues discovered acoustic cues for the perception of phonetic segments (consonants and vowels).

Dominant systems in the 1980s and 1990s were the DECtalk system, based largely on the work of Dennis Klatt at MIT, and the Bell Labs system; the latter was one of the first multilingual language-independent systems, making extensive use of natural language processing methods.

Early electronic speech-synthesizers sounded robotic and were often barely intelligible. The quality of synthesized speech has steadily improved, but as of 2016 output from contemporary speech synthesis systems remains clearly distinguishable from actual human speech.

Kurzweil predicted in 2005 that as the cost-performance ratio caused speech synthesizers to become cheaper and more accessible, more people would benefit from the use of text-to-speech programs.


Computer and speech synthesiser housing used by Stephen Hawking in 1999

The first computer-based speech-synthesis systems originated in the late 1950s. Noriko Umeda et al. developed the first general English text-to-speech system in 1968 at the Electrotechnical Laboratory, Japan. In 1961 physicist John Larry Kelly, Jr and his colleague Louis Gerstman used an IBM 704
IBM 704
computer to synthesize speech, an event among the most prominent in the history of Bell Labs . Kelly's voice recorder synthesizer (vocoder ) recreated the song " Daisy Bell ", with musical accompaniment from Max Mathews . Coincidentally, Arthur C. Clarke was visiting his friend and colleague John Pierce at the Bell Labs Murray Hill facility. Clarke was so impressed by the demonstration that he used it in the climactic scene of his screenplay for his novel 2001: A Space Odyssey , where the HAL 9000 computer sings the same song as astronaut Dave Bowman puts it to sleep. Despite the success of purely electronic speech synthesis, research into mechanical speech-synthesizers continues.

electronics featuring speech synthesis began emerging in the 1970s. One of the first was the Telesensory Systems Inc. (TSI) Speech+ portable calculator for the blind in 1976. Other devices had primarily educational purposes, such as the Speak & Spell toy produced by Texas Instruments in 1978. Fidelity released a speaking version of its electronic chess computer in 1979. The first video game to feature speech synthesis was the 1980 shoot \'em up arcade game , Stratovox (known in Japan as Speak "> although it continues to be used in research because there are a number of freely available software implementations.

Domain-specific Synthesis

Domain-specific synthesis concatenates prerecorded words and phrases to create complete utterances. It is used in applications where the variety of texts the system will output is limited to a particular domain, like transit schedule announcements or weather reports. The technology is very simple to implement, and has been in commercial use for a long time, in devices like talking clocks and calculators. The level of naturalness of these systems can be very high because the variety of sentence types is limited, and they closely match the prosody and intonation of the original recordings.

Because these systems are limited by the words and phrases in their databases, they are not general-purpose and can only synthesize the combinations of words and phrases with which they have been preprogrammed. The blending of words within naturally spoken language however can still cause problems unless the many variations are taken into account. For example, in non-rhotic dialects of English the "r" in words like "clear" /ˈklɪə/ is usually only pronounced when the following word has a vowel as its first letter (e.g. "clear out" is realized as /ˌklɪəɾˈʌʊt/). Likewise in French , many final consonants become no longer silent if followed by a word that begins with a vowel, an effect called liaison . This alternation cannot be reproduced by a simple word-concatenation system, which would require additional complexity to be context-sensitive .


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 ). Parameters such as fundamental frequency , 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 systems , where 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 intonations 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 "1325" may also be read as "one three two five", "thirteen twenty-five" or "thirteen hundred and twenty five". A TTS system can often infer how to expand a number based on surrounding words, numbers, and punctuation, and sometimes the system provides a way to specify the context if it is ambiguous. Roman numerals can also be read differently depending on context. For example, "Henry VIII" reads as "Henry the Eighth", while "Chapter VIII" reads as "Chapter Eight".

Similarly, abbreviations can be ambiguous. For example, the abbreviation "in" for "inches" must be differentiated from the word "in", and the address "12 St John St." uses the same abbreviation for both "Saint" and "Street". TTS systems with intelligent front ends can make educated guesses about ambiguous abbreviations, while others provide the same result in all cases, resulting in nonsensical (and sometimes comical) outputs, such as "co-operation" being rendered as "company operation".


synthesis systems use two basic approaches to determine the pronunciation of a word based on its spelling , a process which is often called text-to-phoneme or grapheme -to-phoneme conversion (phoneme is the term used by linguists to describe distinctive sounds in a language ). The simplest approach to text-to-phoneme conversion is the dictionary-based approach, where a large dictionary containing all the words of a language and their correct pronunciations is stored by the program. Determining the correct pronunciation of each word is a matter of looking up each word in the dictionary and replacing the spelling with the pronunciation specified in the dictionary. The other approach is rule-based, in which pronunciation rules are applied to words to determine their pronunciations based on their spellings. This is similar to the "sounding out", or synthetic phonics , approach to learning reading.

Each approach has advantages and drawbacks. The dictionary-based approach is quick and accurate, but completely fails if it is given a word which is not in its dictionary. As dictionary size grows, so too does the memory space requirements of the synthesis system. On the other hand, the rule-based approach works on any input, but the complexity of the rules grows substantially as the system takes into account irregular spellings or pronunciations. (Consider that the word "of" is very common in English, yet is the only word in which the letter "f" is pronounced .) As a result, nearly all speech synthesis systems use a combination of these approaches.

Languages with a phonemic orthography have a very regular writing system, and the prediction of the pronunciation of words based on their spellings is quite successful. Speech
synthesis systems for such languages often use the rule-based method extensively, resorting to dictionaries only for those few words, like foreign names and borrowings , whose pronunciations are not obvious from their spellings. On the other hand, speech synthesis systems for languages like English , which have extremely irregular spelling systems, are more likely to rely on dictionaries, and to use rule-based methods only for unusual words, or words that aren't in their dictionaries.


The consistent evaluation of speech synthesis systems may be difficult because of a lack of universally agreed objective evaluation criteria. Different organizations often use different speech data. The quality of speech synthesis systems also depends on the quality of the production technique (which may involve analogue or digital recording) and on the facilities used to replay the speech. Evaluating speech synthesis systems has therefore often been compromised by differences between production techniques and replay facilities.

Since 2005, however, some researchers have started to evaluate speech synthesis systems using a common speech dataset.


See also: Prosody (linguistics)

A study in the journal Speech
Communication by Amy Drahota and colleagues at the University of Portsmouth , UK , reported that listeners to voice recordings could determine, at better than chance levels, whether or not the speaker was smiling. It was suggested that identification of the vocal features that signal emotional content may be used to help make synthesized speech sound more natural. One of the related issues is modification of the pitch contour of the sentence, depending upon whether it is an affirmative, interrogative or exclamatory sentence. One of the techniques for pitch modification uses discrete cosine transform in the source domain (linear prediction residual). Such pitch synchronous pitch modification techniques need a priori pitch marking of the synthesis speech database using techniques such as epoch extraction using dynamic plosion index applied on the integrated linear prediction residual of the voiced regions of speech.


Early Technology (not available anymore)

* Icophone

* Votrax

* SC-01A (analog formant) * SC-02 / SSI-263 / "Artic 263"

* General Instrument SP0256-AL2 (CTS256A-AL2) * National Semiconductor DT1050 Digitalker (Mozer – Forrest Mozer ) * Silicon Systems SSI 263 (analog formant)

* Texas Instruments LPC Speech

* TMS5110A * TMS5200 Modern, Human Sounding Text to Speech
on a Chip * MSP50C6XX – Sold to Sensory, Inc. in 2001

* Hitachi HD38880BP (Vanguard Arcade Game SNK 1981)

Current (as of 2013)

* Magnevation SpeakJet (www.speechchips.com) TTS256 Hobby and experimenter. * Epson S1V30120F01A100 (www.epson.com) IC DEC Talk
Based voice, Robotic, Eng/Spanish * Textspeak TTS-EM (www.textspeak.com) ICs, Modules and Industrial enclosures in 24 languages. Human sounding, Phoneme


Popular systems offering speech synthesis as a built-in capability.


The Mattel
game console offered the Intellivoice Voice Synthesis module in 1982. It included the SP0256 Narrator speech synthesizer chip on a removable cartridge. The Narrator had 2kB of Read-Only Memory (ROM), and this was utilized to store a database of generic words that could be combined to make phrases in Intellivision games. Since the Orator chip could also accept speech data from external memory, any additional words or phrases needed could be stored inside the cartridge itself. The data consisted of strings of analog-filter coefficients to modify the behavior of the chip's synthetic vocal-tract model, rather than simple digitized samples.


Also released in 1982, Software
Automatic Mouth was the first commercial all-software voice synthesis program. It was later used as the basis for Macintalk . The program was available for non-Macintosh Apple computers (including the Apple II, and the Lisa), various Atari models and the Commodore 64. The Apple version preferred additional hardware that contained DACs, although it could instead use the computer's one-bit audio output (with the addition of much distortion) if the card was not present. The Atari made use of the embedded POKEY audio chip. Speech
playback on the Atari normally disabled interrupt requests and shut down the ANTIC chip during vocal output. The audible output is extremely distorted speech when the screen is on. The Commodore 64 made use of the 64's embedded SID audio chip.


Arguably, the first speech system integrated into an operating system was the 1400XL/1450XL personal computers designed by Atari, Inc.
Atari, Inc.
using the Votrax SC01 chip in 1983. The 1400XL/1450XL computers used a Finite State Machine to enable World English Spelling text-to-speech synthesis. Unfortunately, the 1400XL/1450XL personal computers never shipped in quantity.

The Atari ST computers were sold with "stspeech.tos" on floppy disk.


The first speech system integrated into an operating system that shipped in quantity was Apple Computer 's MacIn Talk
. The software was licensed from 3rd party developers Joseph Katz and Mark Barton (later, SoftVoice, Inc.) and was featured during the 1984 introduction of the Macintosh computer. This January demo required 512 kilobytes of RAM memory. As a result, it could not run in the 128 kilobytes of RAM the first Mac actually shipped with. So, the demo was accomplished with a prototype 512k Mac, although those in attendance were not told of this and the synthesis demo created considerable excitement for the Macintosh. In the early 1990s Apple expanded its capabilities offering system wide text-to-speech support. With the introduction of faster PowerPC-based computers they included higher quality voice sampling. Apple also introduced speech recognition into its systems which provided a fluid command set. More recently, Apple has added sample-based voices. Starting as a curiosity, the speech system of Apple Macintosh has evolved into a fully supported program, PlainTalk , for people with vision problems. VoiceOver was for the first time featured in Mac OS X Tiger (10.4). During 10.4 (Tiger) & first releases of 10.5 (Leopard) there was only one standard voice shipping with Mac OS X. Starting with 10.6 (Snow Leopard), the user can choose out of a wide range list of multiple voices. VoiceOver voices feature the taking of realistic-sounding breaths between sentences, as well as improved clarity at high read rates over PlainTalk. Mac OS X also includes say , a command-line based application that converts text to audible speech. The AppleScript Standard Additions includes a say verb that allows a script to use any of the installed voices and to control the pitch, speaking rate and modulation of the spoken text.

The Apple iOS operating system used on the iPhone, iPad and iPod Touch uses VoiceOver speech synthesis for accessibility. Some third party applications also provide speech synthesis to facilitate navigating, reading web pages or translating text.


The second operating system to feature advanced speech synthesis capabilities was AmigaOS , introduced in 1985. The voice synthesis was licensed by Commodore International from SoftVoice, Inc., who also developed the original Macin Talk
text-to-speech system. It featured a complete system of voice emulation for American English, with both male and female voices and "stress" indicator markers, made possible through the Amiga
's audio chipset . The synthesis system was divided into a translator library which converted unrestricted English text into a standard set of phonetic codes and a narrator device which implemented a formant model of speech generation.. AmigaOS also featured a high-level "Speak Handler ", which allowed command-line users to redirect text output to speech. Speech
synthesis was occasionally used in third-party programs, particularly word processors and educational software. The synthesis software remained largely unchanged from the first AmigaOS release and Commodore eventually removed speech synthesis support from AmigaOS 2.1 onward.

Despite the American English phoneme limitation, an unofficial version with multilingual speech synthesis was developed. This made use of an enhanced version of the translator library which could translate a number of languages, given a set of rules for each language.


See also: Microsoft Agent

Modern Windows desktop systems can use S API 4 and S API 5 components to support speech synthesis and speech recognition . S API 4.0 was available as an optional add-on for Windows 95 and Windows 98 . Windows 2000 added Narrator , a text–to–speech utility for people who have visual impairment. Third-party programs such as JAWS for Windows, Window-Eyes, Non-visual Desktop Access, Supernova and System Access can perform various text-to-speech tasks such as reading text aloud from a specified website, email account, text document, the Windows clipboard, the user's keyboard typing, etc. Not all programs can use speech synthesis directly. Some programs can use plug-ins, extensions or add-ons to read text aloud. Third-party programs are available that can read text from the system clipboard.

Microsoft Speech
Server is a server-based package for voice synthesis and recognition. It is designed for network use with web applications and call centers .


In the early 1980s, TI was known as a pioneer in speech synthesis, and a highly popular plug-in speech synthesizer module was available for the TI-99/4 and 4A. Speech
synthesizers were offered free with the purchase of a number of cartridges and were used by many TI-written video games (notable titles offered with speech during this promotion were Alpiner and Parsec). The synthesizer uses a variant of linear predictive coding and has a small in-built vocabulary. The original intent was to release small cartridges that plugged directly into the synthesizer unit, which would increase the device's built in vocabulary. However, the success of software text-to-speech in the Terminal Emulator II cartridge cancelled that plan.


TEXT-TO-SPEECH (TTS) refers to the ability of computers to read text aloud. A TTS ENGINE converts written text to a phonemic representation, then converts the phonemic representation to waveforms that can be output as sound. TTS engines with different languages, dialects and specialized vocabularies are available through third-party publishers.


Version 1.6 of Android added support for speech synthesis (TTS).


Currently, there are a number of applications , plugins and gadgets that can read messages directly from an e-mail client and web pages from a web browser or Google Toolbar , such as Text to Voice , which is an add-on to Firefox
. Some specialized software can narrate RSS-feeds . On one hand, online RSS-narrators simplify information delivery by allowing users to listen to their favourite news sources and to convert them to podcasts . On the other hand, on-line RSS-readers are available on almost any PC connected to the Internet. Users can download generated audio files to portable devices, e.g. with a help of podcast receiver, and listen to them while walking, jogging or commuting to work.

A growing field in Internet based TTS is web-based assistive technology , e.g. ' Browsealoud ' from a UK company and Readspeaker . It can deliver TTS functionality to anyone (for reasons of accessibility, convenience, entertainment or information) with access to a web browser. The non-profit project Pediaphon was created in 2006 to provide a similar web-based TTS interface to the .

Other work is being done in the context of the W3C through the W3C Audio Incubator Group with the involvement of The BBC
and Google


Systems that operate on free and open source software systems including Linux
are various, and include open-source programs such as the Festival Speech
Synthesis System which uses diphone-based synthesis, as well as more modern and better-sounding techniques, eSpeak , which supports a broad range of languages, and gnuspeech which uses articulatory synthesis from the Free Software
Foundation .


* Following the commercial failure of the hardware-based Intellivoice, gaming developers sparingly used software synthesis in later games. A famous example is the introductory narration of Nintendo's Super Metroid
Super Metroid
game for the Super Nintendo Entertainment System . Earlier systems from Atari, such as the Atari 5200 (Baseball) and the Atari 2600
Atari 2600
( Quadrun and Open Sesame), also had games utilizing software synthesis. * Some e-book readers , such as the Amazon Kindle , Samsung
E6, PocketBook eReader Pro, enTourage eDGe , and the Bebook Neo. * The BBC Micro incorporated the Texas Instruments TMS5220 speech synthesis chip, * Some models of Texas Instruments home computers produced in 1979 and 1981 ( Texas Instruments TI-99/4 and TI-99/4A ) were capable of text-to-phoneme synthesis or reciting complete words and phrases (text-to-dictionary), using a very popular Speech
Synthesizer peripheral. TI used a proprietary codec to embed complete spoken phrases into applications, primarily video games. * IBM
's OS/2 Warp 4 included VoiceType, a precursor to IBM
ViaVoice . * GPS Navigation units produced by Garmin , Magellan , TomTom
and others use speech synthesis for automobile navigation. * Yamaha
produced a music synthesizer in 1999, the Yamaha
FS1R which included a Formant synthesis capability. Sequences of up to 512 individual vowel and consonant formants could be stored and replayed, allowing short vocal phrases to be synthesized.


With the 2016 introduction of Adobe Voco audio editing and generating software prototype slated to be part of the Adobe Creative Suite
Adobe Creative Suite
and the similarly enabled DeepMind WaveNet , a deep neural network based audio synthesis software from Google
speech synthesis is verging on being completely indistinguishable from a real human's voice.

Adobe Voco takes approximately 20 minutes of the desired target's speech and after that it can generate sound-alike voice with even phonemes that were not present in the training material . The software obviously poses ethical concerns as it allows to steal other peoples voices and manipulate them to say anything desired.

This increases the stress on the disinformation situation coupled with the facts that

* Human image synthesis since the early 2000s has improved beyond the point of human's inability to tell a real human imaged with a real camera from a simulation of a human imaged with a simulation of a camera. * 2D video forgery techniques were presented in 2016 that allow near real-time counterfeiting of facial expressions in existing 2D video.


A number of markup languages have been established for the rendition of text as speech in an XML -compliant format. The most recent is Speech
Synthesis Markup Language (SSML), which became a W3C recommendation in 2004. Older speech synthesis markup languages include Java Speech
Markup Language ( JSML ) and SABLE . Although each of these was proposed as a standard, none of them have been widely adopted.

synthesis markup languages are distinguished from dialogue markup languages. Voice XML , for example, includes tags related to speech recognition, dialogue management and touchtone dialing, in addition to text-to-speech markup.


synthesis has long been a vital assistive technology tool and its application in this area is significant and widespread. It allows environmental barriers to be removed for people with a wide range of disabilities. The longest application has been in the use of screen readers for people with visual impairment , but text-to-speech systems are now commonly used by people with dyslexia and other reading difficulties as well as by pre-literate children. They are also frequently employed to aid those with severe speech impairment usually through a dedicated voice output communication aid .

synthesis techniques are also used in entertainment productions such as games and animations. In 2007, Animo Limited announced the development of a software application package based on its speech synthesis software FineSpeech, explicitly geared towards customers in the entertainment industries, able to generate narration and lines of dialogue according to user specifications. The application reached maturity in 2008, when NEC Biglobe announced a web service that allows users to create phrases from the voices of Code Geass: Lelouch of the Rebellion R2 characters.

In recent years, Text to Speech
for disability and handicapped communication aids have become widely deployed in Mass Transit. Text to Speech
is also finding new applications outside the disability market. For example, speech synthesis, combined with speech recognition , allows for interaction with mobile devices via natural language processing interfaces.

Text-to speech is also used in second language acquisition. Voki, for instance, is an educational tool created by Oddcast that allows users to create their own talking avatar, using different accents. They can be emailed, embedded on websites or shared on social media.

In addition, speech synthesis is a valuable computational aid for the analysis and assessment of speech disorders. A voice quality synthesizer, developed by Jorge C. Lucero et al. at University of Brasilia , simulates the physics of phonation and includes models of vocal frequency jitter and tremor, airflow noise and laryngeal asymmetries. The synthesizer has been used to mimic the timbre of dysphonic speakers with controlled levels of roughness, breathiness and strain.


Multiple companies offer TTS APIs to their customers to accelerate development of new applications utilizing TTS technology. Companies offering TTS APIs include AT"> Stephen Hawking
Stephen Hawking
is one of the most famous people using a speech computer to communicate


* Chinese speech synthesis * Comparison of screen readers * Comparison of speech synthesizers * Euphonia (device) * Paperless office * Speech
processing * Silent speech interface * Text to speech in digital television


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Star Wars
, Firefox
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Gauntlet II
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