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eSpeak

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eSpeakNG
Original author(s)Jonathan Duddington
Developer(s)Reece Dunn
Initial releaseFebruary 2006; 18 years ago (2006-02)
Stable release
1.50 / 2 December 2019; 4 years ago (2019-12-02)
Repositorygithub.com/espeak-ng/espeak-ng/
Written inC
Operating systemLinux
Windows
macOS
FreeBSD
TypeSpeech synthesizer
LicenseGPLv3
Websitegithub.com/espeak-ng/espeak-ng/

eSpeakNG is a compact, open-source, software speech synthesizer for Linux, Windows, and other platforms. It uses a formant synthesis method, providing many languages in a small size. Much of the programming for eSpeakNG's language support is done using rule files with feedback from native speakers.

Because of its small size and many languages, it is included as the default speech synthesizer in the NVDA [1] open source screen reader for Windows, as well as Android,[2] Ubuntu[3] and other Linux distributions. Its predecessor eSpeak was recommended by Microsoft in 2016[4] and was used by Google Translate for 27 languages in 2010;[5] 17 of these were subsequently replaced by commercial voices.[6]

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.[7] 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 computers supporting British English.[8] On 17 February 2006, Speak 1.05 was released under the GPLv2 license, initially for Linux, with a Windows SAPI 5 version added in January 2007.[9] 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)[9] 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,[10] with separate source and binary downloads made available on Sourceforge.[9] From eSpeak 1.27, eSpeak was updated to use the GPLv3 license.[11] 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.[12] The last development release of eSpeak was 1.48.15 on 16 April 2015.[13]

eSpeak uses the Usenet scheme to represent phonemes with ASCII characters.[14]

eSpeak NG

On 25 June 2010,[15] Reece Dunn started a fork of eSpeak on GitHub using the 1.43.46 release. This started off as an effort to make it easier to build eSpeak on Linux and other POSIX 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.[16][17]

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.[18][19] 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.[20] The first release of espeak-ng was 1.49.0 on 10 September 2016,[21] 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 (SSML).

Language voices are identified by the language's ISO 639-1 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 Hello worldⓘ in English.

Synthesis method

ESpeakNG intro by eSpeakNG in English

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

1. step — text to phoneme translation

There are many languages (notably English) which don't 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.

  1. input text is translated into pronunciation phonemes (e.g. input text xerox is translated into zi@r0ks for pronunciation).
  2. pronunciation phonemes are synthesized into sound e.g. zi@r0ks is voiced as zi@r0ks in monotone wayⓘ

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: z'i@r0ks which provides more natural speech: z'i@r0ks with intonationⓘ

For comparison two samples with and without prosody data:

  1. [[DIs Iz m0noUntoUn spi:tS]] is spelled in monotone wayⓘ
  2. [[DIs Iz 'Int@n,eItI2d sp'i:tS]] is spelled intonated wayⓘ

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 speech synthesis using its two different approaches. With its own eSpeakNG synthesizer and a Klatt synthesizer:[22]

  1. The eSpeakNG synthesizer creates voiced speech sounds such as vowels and sonorant consonants by additive synthesis adding together sine waves to make the total sound. Unvoiced consonants e.g. /s/ are made by playing recorded sounds,[23] 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.
  2. The Klatt synthesizer mostly uses the same formant data as the eSpeakNG synthesizer. But, it also produces sounds by subtractive synthesis by starting with generated noise, which is rich in harmonics, and then applying digital filters 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:[24][25]

  1. Abaza
  2. Afrikaans[26]
  3. Albanian[27]
  4. Amharic
  5. Ancient Greek
  6. Arabic1
  7. Aragonese[28]
  8. Armenian (Eastern Armenian)
  9. Armenian (Western Armenian)
  10. Assamese
  11. Azerbaijani
  12. Bashkir
  13. Basque
  14. Belarusian
  15. Bengali
  16. Bhojpuri
  17. Bishnupriya Manipuri
  18. Bosnian
  19. Bulgarian[28]
  20. Burmese
  21. Cantonese[28]
  22. Catalan[28]
  23. Cebuano
  24. Cherokee
  25. Chichewa
  26. Chinese (Mandarin)
  27. Corsican
  28. Croatian[28]
  29. Czech
  30. Chuvash
  31. Danish[28]
  32. Dutch[28]
  33. Dzongkha
  34. English (American)[28]
  35. English (British)
  36. English (Caribbean)
  37. English (Lancastrian)
  38. English (Received Pronunciation)
  39. English (Scottish)
  40. English (West Midlands)
  41. Esperanto[28]
  42. Estonian[28]
  43. Finnish[28]
  44. French (Belgian)[28]
  45. French (France)
  46. French (Swiss)
  47. Frisian
  48. Georgian[28]
  49. German[28]
  50. Greek (Modern)[28]
  51. Greenlandic
  52. Guarani
  53. Gujarati
  54. Hakka Chinese
  55. Haitian Creole
  56. Hausa
  57. Hawaiian
  58. Hebrew
  59. Hindi[28]
  60. Hmong
  61. Hungarian[28]
  62. Icelandic[28]
  63. Igbo
  64. Indonesian[28]
  65. Ido
  66. Interlingua
  67. Irish[28]
  68. Italian[28]
  69. Japanese3[29]
  70. Kannada[28]
  71. Kazakh
  72. Khmer
  73. Klingon
  74. Kʼicheʼ
  75. Konkani[30]
  76. Korean
  77. Kurdish[28]
  78. Kyrgyz
  79. Quechua
  80. Lao
  81. Latin
  82. Latgalian
  83. Latvian[28]
  84. Lingua Franca Nova
  85. Lithuanian
  86. Lojban[28]
  87. Luxembourgish
  88. Macedonian
  89. Maithili
  90. Malagasy
  91. Malay[28]
  92. Malayalam[28]
  93. Maltese
  94. Māori
  95. Marathi[28],
  96. Mongolian
  97. Nahuatl (Classical)
  98. Navajo
  99. Nepali[28]
  100. Norwegian (Bokmål)[28]
  101. Nogai
  102. Odia
  103. Oromo
  104. Papiamento
  105. Pashto
  106. Persian[28]
  107. Persian (Latin alphabet)2
  108. Polish[28]
  109. Portuguese (Brazilian)[28]
  110. Portuguese (Portugal)
  111. Punjabi[31]
  112. Pyash (a constructed language)
  113. Romanian[28]
  114. Russian[28]
  115. Russian (Latvia)
  116. Samoan
  117. Sanskrit
  118. Scottish Gaelic
  119. Serbian[28]
  120. Shan (Tai Yai),
  121. Sharda
  122. Shona
  123. Sindhi
  124. Sinhala
  125. Slovak[28]
  126. Slovenian
  127. Somali
  128. Spanish (Spain)[28]
  129. Spanish (Latin American)
  130. Swahili[26]
  131. Swedish[28]
  132. Tamil[28]
  133. Tatar
  134. Telugu
  135. Tswana
  136. Thai
  137. Turkmen
  138. Turkish[28]
  139. Tatar
  140. Uyghur
  141. Ukrainian
  142. Urdu
  143. Uzbek
  144. Vietnamese (Central Vietnamese)[28]
  145. Vietnamese (Northern Vietnamese)
  146. Vietnamese (Southern Vietnamese)
  147. Valyrian
  148. Welsh
  149. Wolof
  150. Xhosa
  151. Yiddish
  152. Yoruba
  153. Zulu
  1. Currently, only fully diacritized Arabic is supported.
  2. Farsi/Persian written using English (Latin) characters.
  3. Currently, only Hiragana and Katakana are supported.

See also

References

  1. ^ Switch to eSpeak NG in NVDA distribution #5651
  2. ^ eSpeak TTS for Android
  3. ^ espeak-ng package in Ubuntu
  4. ^ https://support.office.com/en-us/article/download-voices-for-immersive-reader-read-mode-and-read-aloud-4c83a8d8-7486-42f7-8e46-2b0fdf753130
  5. ^ Google blog, Giving a voice to more languages on Google Translate, May 2010
  6. ^ Google blog, Listen to us now, December 2010.
  7. ^ eSpeak Speech Synthesizer 3. LANGUAGES
  8. ^ http://espeak.sourceforge.net/
  9. ^ a b c https://sourceforge.net/projects/espeak/files/espeak/
  10. ^ Subversion history (revision 1)
  11. ^ Subversion history (revision 56)
  12. ^ http://espeak.sourceforge.net/download.html
  13. ^ http://espeak.sourceforge.net/test/latest.html
  14. ^ van Leussen, Jan-Wilem; Tromp, Maarten (26 July 2007). "Latin to Speech" (Document). p. 6. {{cite document}}: Cite document requires |publisher= (help); Unknown parameter |citeseerx= ignored (help)
  15. ^ https://github.com/rhdunn/espeak/commit/63daaecefccde34b700bd909d23c6dd2cac06e20
  16. ^ https://github.com/rhdunn/espeak/commit/61522a12a38453a4e854fd9c9e0994ad80420243
  17. ^ https://github.com/nvaccess/nvda/issues/5651#issuecomment-170288487
  18. ^ Taking ownership of the eSpeak project and its future
  19. ^ Vote for new main eSpeak developer
  20. ^ Rebrand the espeak program to espeak-ng.
  21. ^ espeak-ng 1.49.0
  22. ^ Dennis H. Klatt (1979). "Software for a cascade/parallel formant synthesizer" (PDF). J. Acoustical Society of America, 67(3) March 1980.
  23. ^ List of recorded fricatives in eSpeakNG
  24. ^ https://github.com/espeak-ng/espeak-ng/blob/master/docs/languages.md
  25. ^ https://github.com/espeak-ng/espeak-ng/blob/master/CHANGELOG.md
  26. ^ a b 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.
  27. ^ Hamiti, M., & Kastrati, R. (2014). Adapting eSpeak for converting text into speech in Albanian. International Journal of Computer Science Issues (IJCSI), 11(4), 21.
  28. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap Kayte, 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.
  29. ^ Pronk, R. (2013). Adding Japanese language synthesis support to the eSpeak system. University of Amsterdam.
  30. ^ Mohanan, S., Salkar, S., Naik, G., Dessai, N. F., & Naik, S. (2012). Text Reader for Konkani Language. Automation and Autonomous System, 4(8), 409-414.
  31. ^ Kaur, 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.
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