eSpeak is a

free and open-source Free and open-source software (FOSS) is software available under a Software license, license that grants users the right to use, modify, and distribute the software modified or not to everyone free of charge. FOSS is an inclusive umbrella term ...

cross-platform Within computing, cross-platform software (also called multi-platform software, platform-agnostic software, or platform-independent software) is computer software that is designed to work in several Computing platform, computing platforms. Some ...

, compact, software speech synthesizer. It uses a formant synthesis method, providing many languages in a relatively small file size. eSpeakNG (Next Generation) is a continuation of the original developer's project with more feedback from native speakers. Because of its small size and many languages, eSpeakNG is included in NVDA open source

screen reader A screen reader is a form of assistive technology (AT) that renders text and image content as speech or braille output. Screen readers are essential to blindness, blind people, and are useful to visually impaired people, Illiteracy, illiterate, ...

for Windows, as well as Android,

Ubuntu Ubuntu ( ) is a Linux distribution based on Debian and composed primarily of free and open-source software. Developed by the British company Canonical (company), Canonical and a community of contributors under a Meritocracy, meritocratic gover ...

and other Linux distributions. Its predecessor eSpeak was recommended by Microsoft in 2016 and was used by

Google Translate Google Translate is a multilingualism, multilingual neural machine translation, neural machine translation service developed by Google to translation, translate text, documents and websites from one language into another. It offers a web applic ...

for 27 languages in 2010; 17 of these were subsequently replaced by proprietary voices. The quality of the language voices varies greatly. In eSpeakNG's predecessor eSpeak, the initial versions of some languages were based on information found on

Wikipedia Wikipedia is a free content, free Online content, online encyclopedia that is written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and the wiki software MediaWiki. Founded by Jimmy Wales and La ...

. Some languages have had more work or feedback from native speakers than others. Most of the people who have helped to improve the various languages are blind users of text-to-speech.

History

In 1995, Jonathan Duddington released the Speak speech synthesizer for

RISC OS RISC OS () is an operating system designed to run on ARM architecture, ARM computers. Originally designed in 1987 by Acorn Computers of England, it was made for use in its new line of ARM-based Acorn Archimedes, Archimedes personal computers an ...

computers supporting British English. On 17 February 2006, Speak 1.05 was released under the

GPLv2 The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or copyleft, ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was th ...

license, initially for

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

, with a Windows SAPI 5 version added in January 2007. Development on Speak continued until version 1.14, when it was renamed to eSpeak. Development of eSpeak continued from 1.16 (there was not a 1.15 release) with the addition of an eSpeakEdit program for editing and building the eSpeak voice data. These were only available as separate source and binary downloads up to eSpeak 1.24. The 1.24.02 version of eSpeak was the first version of eSpeak to be version controlled using

subversion Subversion () refers to a process by which the values and principles of a system in place are contradicted or reversed in an attempt to sabotage the established social order and its structures of Power (philosophy), power, authority, tradition, h ...

, with separate source and binary downloads made available on SourceForge. From eSpeak 1.27, eSpeak was updated to use the

GPLv3 The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...

license. The last official eSpeak release was 1.48.04 for Windows and Linux, 1.47.06 for RISC OS and 1.45.04 for

macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...

. The last development release of eSpeak was 1.48.15 on 16 April 2015. eSpeak uses the Usenet scheme to represent

phoneme A phoneme () is any set of similar Phone (phonetics), speech sounds that are perceptually regarded by the speakers of a language as a single basic sound—a smallest possible Phonetics, phonetic unit—that helps distinguish one word fr ...

s with ASCII characters.

eSpeak NG

On 25 June 2010, Reece Dunn started a fork of eSpeak on

GitHub GitHub () is a Proprietary software, proprietary developer platform that allows developers to create, store, manage, and share their code. It uses Git to provide distributed version control and GitHub itself provides access control, bug trackin ...

using the 1.43.46 release. This started off as an effort to make it easier to build eSpeak on Linux and other

POSIX The Portable Operating System Interface (POSIX; ) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines application programming interfaces (APIs), along with comm ...

platforms. On 4 October 2015 (6 months after the 1.48.15 release of eSpeak), this fork started diverging more significantly from the original eSpeak. On 8 December 2015, there were discussions on the eSpeak mailing list about the lack of activity from Jonathan Duddington over the previous 8 months from the last eSpeak development release. This evolved into discussions of continuing development of eSpeak in Jonathan's absence. The result of this was the creation of the espeak-ng (Next Generation) fork, using the GitHub version of eSpeak as the basis for future development. On 11 December 2015, the espeak-ng fork was started. The first release of espeak-ng was 1.49.0 on 10 September 2016, containing significant code cleanup, bug fixes, and language updates.

Features

eSpeakNG can be used as a command-line program, or as a shared library. It supports

Speech Synthesis Markup Language Speech Synthesis Markup Language (SSML) is an XML-based markup language for speech synthesis applications. It is a recommendation of the W3C's Voice Browser Working Group. SSML is often embedded in VoiceXML scripts to drive interactive telephony sy ...

(SSML). Language voices are identified by the language's

ISO 639-1 ISO 639-1:2002, ''Codes for the representation of names of languages—Part 1: Alpha-2 code'', is the first part of the ISO 639 series of international standards for language codes. Part 1 covers the registration of "set 1" two-letter codes. The ...

code. They can be modified by "voice variants". These are text files which can change characteristics such as pitch range, add effects such as echo, whisper and croaky voice, or make systematic adjustments to formant frequencies to change the sound of the voice. For example, "af" is the Afrikaans voice. "af+f2" is the Afrikaans voice modified with the "f2" voice variant which changes the formants and the pitch range to give a female sound. eSpeakNG uses an ASCII representation of phoneme names which is loosely based on the Usenet system. Phonetic representations can be included within text input by including them within double square-brackets. For example: espeak-ng -v en "Hello w3:ld" will say in English.

Synthesis method

eSpeakNG can be used as a text-to-speech translator in different ways, depending on which text-to-speech translation step the user wants to use.

1. step – text to phoneme translation

There are many languages (notably English) which do not have straightforward one-to-one rules between writing and pronunciation; therefore, the first step in text-to-speech generation has to be text-to-phoneme translation. #input text is translated into pronunciation phonemes (e.g. input text ''xerox'' is translated into for pronunciation). #pronunciation phonemes are synthesized into sound e.g., is voiced as To add intonation for speech i.e. prosody data are necessary (e.g. stress of syllable, falling or rising pitch of basic frequency, pause, etc.) and other information, which allows to synthesize more human, non-monotonous speech. E.g. in eSpeakNG format stressed syllable is added using apostrophe: which provides more natural speech: For comparison two samples with and without prosody data: # is spelled # is spelled If eSpeakNG is used for generation of prosody data only, then prosody data can be used as input for MBROLA diphone voices.

2. step – sound synthesis from prosody data

The eSpeakNG provides two different types of

formant In speech science and phonetics, a formant is the broad spectral maximum that results from an acoustic resonance of the human vocal tract. In acoustics, a formant is usually defined as a broad peak, or local maximum, in the spectrum. For harmo ...

speech synthesis Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal langua ...

using its two different approaches. With its own eSpeakNG synthesizer and a ''Klatt synthesizer'': #The eSpeakNG synthesizer creates voiced speech sounds such as

vowel A vowel is a speech sound pronounced without any stricture in the vocal tract, forming the nucleus of a syllable. Vowels are one of the two principal classes of speech sounds, the other being the consonant. Vowels vary in quality, in loudness a ...

s and sonorant consonants by

additive synthesis Additive synthesis is a sound synthesis technique that creates timbre by adding sine waves together. The timbre of musical instruments can be considered in the light of Fourier series, Fourier theory to consist of multiple harmonic or inharmoni ...

adding together sine waves to make the total sound. Unvoiced consonants e.g. /s/ are made by playing recorded sounds, because they are rich in harmonics, which makes additive synthesis less effective. Voiced consonants such as /z/ are made by mixing a synthesized voiced sound with a recorded sample of unvoiced sound. #The Klatt synthesizer mostly uses the same formant data as the eSpeakNG synthesizer. But, it also produces sounds by

subtractive synthesis Subtractive synthesis is a method of sound synthesis in which Harmonic_series_(music)#Partial.2C_harmonic.2C_fundamental.2C_inharmonicity.2C_and_overtone, overtones of an audio signal are attenuated by a audio filter, filter to alter the timbre of ...

by starting with generated noise, which is rich in harmonics, and then applying

digital filter In signal processing, a digital filter is a system that performs mathematical operations on a Sampling (signal processing), sampled, discrete-time signal to reduce or enhance certain aspects of that signal. This is in contrast to the other ma ...

s and enveloping to filter out necessary frequency spectrum and sound envelope for particular consonant (s, t, k) or sonorant (l, m, n) sound. For the MBROLA voices, eSpeakNG converts the text to phonemes and associated pitch contours. It passes this to the MBROLA program using the PHO file format, capturing the audio created in output by MBROLA. That audio is then handled by eSpeakNG.

Languages

eSpeakNG performs text-to-speech synthesis for the following languages: #

Afrikaans Afrikaans is a West Germanic languages, West Germanic language spoken in South Africa, Namibia and to a lesser extent Botswana, Zambia, Zimbabwe and also Argentina where there is a group in Sarmiento, Chubut, Sarmiento that speaks the Pat ...

Butgereit, L., & Botha, A. (2009, May)
Hadeda: The noisy way to practice spelling vocabulary using a cell phone
In ''The IST-Africa 2009 Conference, Kampala, Uganda''. # Albanian #

Amharic Amharic is an Ethio-Semitic language, which is a subgrouping within the Semitic branch of the Afroasiatic languages. It is spoken as a first language by the Amhara people, and also serves as a lingua franca for all other metropolitan populati ...

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...

¹ # AragoneseKayte, S., & Gawali, D. B. (2015). Marathi Speech Synthesis: A review. International Journal on Recent and Innovation Trends in Computing and Communication, 3(6), 3708-3711. #

Armenian Armenian may refer to: * Something of, from, or related to Armenia, a country in the South Caucasus region of Eurasia * Armenians, the national people of Armenia, or people of Armenian descent ** Armenian diaspora, Armenian communities around the ...

(

Eastern Armenian Eastern Armenian () is one of the two standardized forms of Modern Armenian, the other being Western Armenian. The two standards form a pluricentric language. Eastern Armenian is spoken in Armenia, Russia, as well as Georgia, and by the Armeni ...

) #

(

Western Armenian Western Armenian ( ) is one of the two standardized forms of Modern Armenian, the other being Eastern Armenian. It is based mainly on the Istanbul Armenian dialect, as opposed to Eastern Armenian, which is mainly based on the Yerevan Arme ...

) # Assamese # Azerbaijani # Bashkir #

Basque Basque may refer to: * Basques, an ethnic group of Spain and France * Basque language, their language Places * Basque Country (greater region), the homeland of the Basque people with parts in both Spain and France * Basque Country (autonomous co ...

# Belarusian # Bengali # Bishnupriya Manipuri # Bosnian # Bulgarian # Burmese #

Cantonese Cantonese is the traditional prestige variety of Yue Chinese, a Sinitic language belonging to the Sino-Tibetan language family. It originated in the city of Guangzhou (formerly known as Canton) and its surrounding Pearl River Delta. While th ...

# Catalan #

Cherokee The Cherokee (; , or ) people are one of the Indigenous peoples of the Southeastern Woodlands of the United States. Prior to the 18th century, they were concentrated in their homelands, in towns along river valleys of what is now southwestern ...

# Chinese (

Mandarin Mandarin or The Mandarin may refer to: Language * Mandarin Chinese, branch of Chinese originally spoken in northern parts of the country ** Standard Chinese or Modern Standard Mandarin, the official language of China ** Taiwanese Mandarin, Stand ...

) # Croatian #

Czech Czech may refer to: * Anything from or related to the Czech Republic, a country in Europe ** Czech language ** Czechs, the people of the area ** Czech culture ** Czech cuisine * One of three mythical brothers, Lech, Czech, and Rus *Czech (surnam ...

# Chuvash # Danish # Dutch # English ( American) # English (

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...

) # English (

Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...

) # English ( Lancastrian) # English (

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

)⁵ # English (

Received Pronunciation Received Pronunciation (RP) is the Accent (sociolinguistics), accent of British English regarded as the Standard language, standard one, carrying the highest Prestige (sociolinguistics), social prestige, since as late as the beginning of the 2 ...

) # English ( Scottish) # English ( West Midlands) #

Esperanto Esperanto (, ) is the world's most widely spoken Constructed language, constructed international auxiliary language. Created by L. L. Zamenhof in 1887 to be 'the International Language' (), it is intended to be a universal second language for ...

# Estonian # Finnish # French ( Belgian) # French (

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

) # French (

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

) # Georgian # German #

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

( Modern) # Greenlandic # Guarani # Gujarati #

Hakka Chinese Hakka ( zh, c=, p=Kèjiāhuà; '' Pha̍k-fa-sṳ: '', zh, c=, p=Kèjiāyǔ; '' Pha̍k-fa-sṳ: '') forms a language group of varieties of Chinese, spoken natively by the Hakka people in parts of Southern China, Taiwan, some diaspora areas ...

³ #

Haitian Creole Haitian Creole (; , ; , ), or simply Creole (), is a French-based creole languages, French-based creole language spoken by 10 to 12million people worldwide, and is one of the two official languages of Haiti (the other being French), where it ...

# Hawaiian #

Hebrew Hebrew (; ''ʿÎbrit'') is a Northwest Semitic languages, Northwest Semitic language within the Afroasiatic languages, Afroasiatic language family. A regional dialect of the Canaanite languages, it was natively spoken by the Israelites and ...

Hindi Modern Standard Hindi (, ), commonly referred to as Hindi, is the Standard language, standardised variety of the Hindustani language written in the Devanagari script. It is an official language of India, official language of the Government ...

# Hungarian # Icelandic # Indonesian #

Ido Ido () is a constructed language derived from a reformed version of Esperanto, and designed similarly with the goal of being a universal second language for people of diverse languages. To function as an effective ''international auxiliary ...

Interlingua Interlingua (, ) is an international auxiliary language (IAL) developed between 1937 and 1951 by the American International Auxiliary Language Association (IALA). It is a constructed language of the "naturalistic" variety, whose vocabulary, ...

# Irish #

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

# Japanese⁴ #

Kannada Kannada () is a Dravidian language spoken predominantly in the state of Karnataka in southwestern India, and spoken by a minority of the population in all neighbouring states. It has 44 million native speakers, and is additionally a ...

# Kazakh #

Klingon The Klingons ( ; Klingon language, Klingon: ''tlhIngan'' ) are a humanoid species of aliens in the science fiction franchise ''Star Trek''. Developed by screenwriter Gene L. Coon in 1967 for the Star Trek: The Original Series, original ''Star T ...

# Kʼicheʼ #

Konkani __NOTOC__ Konkani may refer to: Language * Konkani language is an Indo-Aryan language spoken in the Konkan region of India. * Konkani alphabets, different scripts used to write the language **Konkani in the Roman script, one of the scripts used to ...

# Korean # Kurdish # Kyrgyz # Quechua #

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

# Latgalian # Latvian #

Lingua Franca Nova Lingua Franca Nova (), abbreviated as LFN and known colloquially as Elefen, is a constructed international auxiliary language originally created by C. George Boeree of Shippensburg University, Pennsylvania, and further developed by many of its ...

# Lithuanian #

Lojban Lojban (pronounced ) is a Logical language, logical, constructed language, constructed, human language created by the Logical Language Group which aims to be Syntactic ambiguity, syntactically unambiguous. It succeeds the Loglan project. The Log ...

Luxembourgish Luxembourgish ( ; also ''Luxemburgish'', ''Luxembourgian'', ''Letzebu(e)rgesch''; ) is a West Germanic language that is spoken mainly in Luxembourg. About 400,000 people speak Luxembourgish worldwide. The language is standardized and officiall ...

# Macedonian # Malay #

Malayalam Malayalam (; , ) is a Dravidian languages, Dravidian language spoken in the Indian state of Kerala and the union territories of Lakshadweep and Puducherry (union territory), Puducherry (Mahé district) by the Malayali people. It is one of ...

# Maltese # Manipuri # Māori # Marathi #

Nahuatl Nahuatl ( ; ), Aztec, or Mexicano is a language or, by some definitions, a group of languages of the Uto-Aztecan language family. Varieties of Nahuatl are spoken by about Nahuas, most of whom live mainly in Central Mexico and have smaller popul ...

( Classical) # Nepali # Norwegian (

Bokmål Bokmål () (, ; ) is one of the official written standards for the Norwegian language, alongside Nynorsk. Bokmål is by far the most used written form of Norwegian today, as it is adopted by 85% to 90% of the population in Norway. There is no cou ...

) # Nogai # Oromo #

Papiamento Papiamento () or Papiamentu (; ) is a Portuguese-based creole language spoken in the Dutch Caribbean. It is the most widely spoken language on Aruba, Bonaire, and Curaçao ( ABC Islands). The language, spelled in Aruba and in Bonaire and ...

# Persian # Persian (

Latin alphabet The Latin alphabet, also known as the Roman alphabet, is the collection of letters originally used by the Ancient Rome, ancient Romans to write the Latin language. Largely unaltered except several letters splitting—i.e. from , and from � ...

)² # Polish # Portuguese ( Brazilian) # Portuguese (

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

) # PunjabiKaur, R., & Sharma, D. (2016)
An Improved System for Converting Text into Speech for Punjabi Language using eSpeak
''International Research Journal of Engineering and Technology'', 3(4), 500-504. #Pyash (a

constructed language A constructed language (shortened to conlang) is a language whose phonology, grammar, orthography, and vocabulary, instead of having developed natural language, naturally, are consciously devised for some purpose, which may include being devise ...

) #

Quenya Quenya ()Tolkien wrote in his "Outline of Phonology" (in '' Parma Eldalamberon'' 19, p. 74) dedicated to the phonology of Quenya: is "a sound as in English ''new''". In Quenya is a combination of consonants, ibidem., p. 81. is a constructed l ...

# Romanian # Russian # Russian (

Latvia Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to t ...

) #

Scottish Gaelic Scottish Gaelic (, ; Endonym and exonym, endonym: ), also known as Scots Gaelic or simply Gaelic, is a Celtic language native to the Gaels of Scotland. As a member of the Goidelic language, Goidelic branch of Celtic, Scottish Gaelic, alongs ...

# Serbian # Setswana # Shan (Tai Yai) # Sindarin # Sindhi # Sinhala # Slovak # Slovenian # Spanish (

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

) # Spanish (

Latin American Latin Americans (; ) are the citizenship, citizens of Latin American countries (or people with cultural, ancestral or national origins in Latin America). Latin American countries and their Latin American diaspora, diasporas are Metroethnicity, ...

) # Swahili # Swedish #

Tamil Tamil may refer to: People, culture and language * Tamils, an ethno-linguistic group native to India, Sri Lanka, and some other parts of Asia **Sri Lankan Tamils, Tamil people native to Sri Lanka ** Myanmar or Burmese Tamils, Tamil people of Ind ...

# Tatar # Telugu # Thai # Turkmen # Turkish # Uyghur # Ukrainian #

Urarina The Urarina are an indigenous people of the Peruvian Amazon Basin (Loreto (Department of Peru), Loreto) who inhabit the valleys of the Chambira, Urituyacu, and Corrientes Rivers. According to both archaeological and historical sources, they have ...

Urdu Urdu (; , , ) is an Indo-Aryan languages, Indo-Aryan language spoken chiefly in South Asia. It is the Languages of Pakistan, national language and ''lingua franca'' of Pakistan. In India, it is an Eighth Schedule to the Constitution of Indi ...

# Uzbek # Vietnamese ( Central Vietnamese) # Vietnamese ( Northern Vietnamese) # Vietnamese ( Southern Vietnamese) # Welsh #Currently, only fully diacritized Arabic is supported. # Persian written using English (Latin) characters. #Currently, only

Pha̍k-fa-sṳ Pha̍k-fa-sṳ () is an orthography similar to Pe̍h-ōe-jī and used to write Hakka, a variety of Chinese. Hakka is a whole branch of Chinese, and Hakka dialects are not necessarily mutually intelligible with each other, considering the large geo ...

is supported. #Currently, only

Hiragana is a Japanese language, Japanese syllabary, part of the Japanese writing system, along with ''katakana'' as well as ''kanji''. It is a phonetic lettering system. The word ''hiragana'' means "common" or "plain" kana (originally also "easy", ...

and

Katakana is a Japanese syllabary, one component of the Japanese writing system along with hiragana, kanji and in some cases the Latin script (known as rōmaji). The word ''katakana'' means "fragmentary kana", as the katakana characters are derived fr ...

are supported. #Currently unreleased; it must be built from the latest source code.

References

External links

eSpeakNG on GitHub
{{Speech synthesis Free software programmed in C Free speech synthesis software GNOME Accessibility Open source software synthesizers