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eSpeakNG
Original authorJonathan Duddington
DeveloperAlexander Epaneshnikov et al.
Initial releaseFebruary 2006; 19 years ago (2006-02)
Stable release
1.51[1] Edit this on Wikidata / 2 April 2022; 3 years ago (2 April 2022)
Repositorygithub.com/espeak-ng/espeak-ng/
Written inC
Operating systemLinux
Windows
macOS
FreeBSD
TypeSpeech synthesizer
LicenseGPLv3
Websitegithub.com/espeak-ng/espeak-ng/

eSpeak is a free and open-source, cross-platform, 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[2] open source screen reader for Windows, as well as Android,[3] Ubuntu[4] and other Linux distributions. Its predecessor eSpeak was recommended by Microsoft in 2016[5] and was used by Google Translate for 27 languages in 2010;[6] 17 of these were subsequently replaced by proprietary voices.[7]

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.[8] 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

[edit]

In 1995, Jonathan Duddington released the Speak speech synthesizer for RISC OS computers supporting British English.[9] 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.[10] 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)[10] 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,[11] with separate source and binary downloads made available on SourceForge.[10] 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

[edit]

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

[edit]

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

[edit]
ESpeakNG intro by eSpeakNG in English

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

[edit]

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.

  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

[edit]

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

[edit]

eSpeakNG performs text-to-speech synthesis for the following languages:[24]

  1. Afrikaans[25]
  2. Albanian[26]
  3. Amharic
  4. Ancient Greek
  5. Arabic[a]
  6. Aragonese[27]
  7. Armenian (Eastern Armenian)
  8. Armenian (Western Armenian)
  9. Assamese
  10. Azerbaijani
  11. Bashkir
  12. Basque
  13. Belarusian
  14. Bengali
  15. Bishnupriya Manipuri
  16. Bosnian
  17. Bulgarian[27]
  18. Burmese
  19. Cantonese[27]
  20. Catalan[27]
  21. Cherokee
  22. Chinese (Mandarin)
  23. Croatian[27]
  24. Czech
  25. Chuvash
  26. Danish[27]
  27. Dutch[27]
  28. English (American)[27]
  29. English (British)
  30. English (Caribbean)
  31. English (Lancastrian)
  32. English (New York City)[b]
  33. English (Received Pronunciation)
  34. English (Scottish)
  35. English (West Midlands)
  36. Esperanto[27]
  37. Estonian[27]
  38. Finnish[27]
  39. French (Belgian)[27]
  40. French (Canada)
  41. French (France)
  42. Georgian[27]
  43. German[27]
  44. Greek (Modern)[27]
  45. Greenlandic
  46. Guarani
  47. Gujarati
  48. Hakka Chinese[c]
  49. Haitian Creole
  50. Hawaiian
  51. Hebrew
  52. Hindi[27]
  53. Hungarian[27]
  54. Icelandic[27]
  55. Indonesian[27]
  56. Ido
  57. Interlingua
  58. Irish[27]
  59. Italian[27]
  60. Japanese[d][28]
  61. Kannada[27]
  62. Kazakh
  63. Klingon
  64. Kʼicheʼ
  65. Konkani[29]
  66. Korean
  67. Kurdish[27]
  68. Kyrgyz
  69. Quechua
  70. Latin
  71. Latgalian
  72. Latvian[27]
  73. Lingua Franca Nova
  74. Lithuanian
  75. Lojban[27]
  76. Luxembourgish
  77. Macedonian
  78. Malay[27]
  79. Malayalam[27]
  80. Maltese
  81. Manipuri
  82. Māori
  83. Marathi[27]
  84. Nahuatl (Classical)
  85. Nepali[27]
  86. Norwegian (Bokmål)[27]
  87. Nogai
  88. Oromo
  89. Papiamento
  90. Persian[27]
  91. Persian (Latin alphabet)
  92. Polish[27]
  93. Portuguese (Brazilian)[27]
  94. Portuguese (Portugal)
  95. Punjabi[30]
  96. Pyash (a constructed language)
  97. Quenya
  98. Romanian[27]
  99. Russian[27]
  100. Russian (Latvia)
  101. Scottish Gaelic
  102. Serbian[27]
  103. Setswana
  104. Shan (Tai Yai)
  105. Sindarin
  106. Sindhi
  107. Sinhala
  108. Slovak[27]
  109. Slovenian
  110. Spanish (Spain)[27]
  111. Spanish (Latin American)
  112. Swahili[25]
  113. Swedish[27]
  114. Tamil[27]
  115. Tatar
  116. Telugu
  117. Thai
  118. Turkmen
  119. Turkish[27]
  120. Uyghur
  121. Ukrainian
  122. Urarina
  123. Urdu
  124. Uzbek
  125. Vietnamese (Central Vietnamese)[27]
  126. Vietnamese (Northern Vietnamese)
  127. Vietnamese (Southern Vietnamese)
  128. Welsh
  1. ^ Currently, only fully diacritized Arabic is supported.
  2. ^ Currently unreleased; it must be built from the latest source code.
  3. ^ Currently, only Pha̍k-fa-sṳ is supported.
  4. ^ Currently, only Hiragana and Katakana are supported.

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

ESpeak

View on Grokipedia
from Grokipedia
eSpeak is a compact, speech that employs synthesis to generate clear but synthetic-sounding speech from text in English and numerous other languages. It supports multiple platforms, including and Windows, and is available as a command-line program, , or SAPI5-compatible version for applications. With a total size of approximately 2 megabytes, including support for many languages, eSpeak prioritizes efficiency and portability while producing speech at high speeds. Originally developed by Jonathan Duddington, eSpeak traces its roots to an earlier project called "speak," created in 1995 for the / platform, which was later enhanced and rewritten in 2007 as eSpeak with relaxed licensing and expanded language capabilities. The synthesizer uses a -based approach, allowing it to translate text into speech via custom dictionaries and rules, and it can output to files or integrate with tools like MBROLA for alternative voice synthesis. Key features include support for (SSML) and reading, multiple voice variants (such as male/female or whisper modes), and the ability to edit data using the included espeakedit tool. The original eSpeak project, hosted on , has been largely succeeded by eSpeak NG, an active open-source initiated in late 2015 to modernize the codebase, add new features, and expand language support to over 100 languages and accents. eSpeak NG maintains compatibility with the original while incorporating improvements like Klatt formant synthesis, enhanced MBROLA integration, and ports to additional platforms such as Android, macOS, and BSD systems. Both versions are licensed under the GPL and continue to be used in assistive technologies, embedded systems, and text-to-speech applications worldwide.

History

Initial Development

The initial development of eSpeak traces back to 1995, when Jonathan Duddington created the "speak" program for Acorn/RISC OS computers, initially supporting British English as a compact speech synthesizer. This early version was designed with efficiency in mind, targeting the limited resources of RISC OS systems, and laid the foundation for formant-based synthesis techniques that would define the project. In 2007, Duddington enhanced and rewrote the program, renaming it eSpeak to reflect its expanded capabilities, including relaxed memory and processing constraints that enabled broader applicability beyond RISC OS. The first public release of eSpeak occurred around this time, establishing it as an open-source, formant-based text-to-speech synthesizer initially focused on English but quickly incorporating support for other languages. Key enhancements under Duddington's solo development included porting to multiple platforms such as Linux and Windows, which broadened its accessibility, and introducing initial multi-language support through rule-based phoneme conversion. Duddington maintained active development through numerous iterations, with version history progressing from early releases in the to more refined builds addressing prosody, voice variants, and language dictionaries. The last major release, eSpeak 1.48 (including subversions like 1.48.04), was issued in 2015, incorporating improvements in synthesis quality and platform integration before development slowed. His passing marked the endpoint of this individual-led phase, after which the project briefly transitioned to community-driven open-source maintenance in the form of eSpeak NG.

eSpeak NG Continuation

eSpeak NG was forked from the original eSpeak project in late 2015 to improve maintainability and enable ongoing development through a more collaborative structure. Following the passing of the original developer Jonathan Duddington, the project saw increased activity from a community of volunteers. The project transitioned to a dedicated repository under the espeak-ng organization, where volunteer developers, including native speakers, contribute feedback to refine language rules and pronunciations. This open-source effort has focused on enhancing compatibility and quality through iterative contributions. Key releases include version 1.50 in December 2019, which introduced support for SSML <phoneme> tags, along with support for nine new languages such as Bashkir. Version 1.51 in April 2022 added features like voice variants and a extension, while expanding language coverage with over 20 new additions including Belarusian, and improving platform integrations such as for Android. The latest release, 1.52 in December 2024, added a build system, stress marks for improved prosody, along with bug fixes and six new languages like Tigrinya. Community-driven improvements have emphasized better prosody through additions like stress marks in phoneme events and integration with modern toolchains, including a new build system to replace the older approach. As of 2025, eSpeak NG remains an active project, with over 500 issues resolved on and support for more than 100 languages and accents.

Overview and Features

Core Functionality

eSpeak is a free and open-source, speech synthesizer designed to convert written text into audible speech. It operates primarily through synthesis, a method that generates speech by modeling the resonances of the human vocal tract, resulting in a compact suitable for resource-constrained devices. The core , including the program and data files for multiple languages, occupies less than 2 MB, making it lightweight and efficient for embedded systems or low-power environments. At its foundation, eSpeak provides a straightforward for basic text-to-speech operations, allowing users to input text directly via commands such as espeak-ng "Hello, world" to produce spoken output from files, standard input, or strings. For more advanced programmatic use, it offers an through a (or DLL on Windows), enabling developers to integrate into applications for automated reading of text. This supports embedding eSpeak within software for tasks like screen readers or voice assistants. eSpeak incorporates support for (SSML), which allows fine-grained control over speech attributes including pitch, speaking rate, and volume through markup tags in the input text. Output can be directed in various formats, such as generating audio files for storage, playing audio directly through the system's sound device, or piping the synthesized speech to other command-line tools for further processing. These capabilities ensure versatility in both standalone and integrated scenarios.

Advantages and Limitations

eSpeak demonstrates significant advantages in portability, supporting a wide range of operating systems including , Windows, Android (version 4.0 and later), BSD, Solaris, and macOS through command-line interfaces, shared libraries, and Windows SAPI5 compatibility. Its formant synthesis method enables rapid processing, achieving practical synthesis speeds of up to 500 words per minute, which facilitates efficient real-time applications. Additionally, eSpeak's compact footprint—totaling just a few megabytes—allows it to operate on resource-constrained embedded systems with minimal computational demands. As an open-source project licensed under the GPL-3.0 or later, it is freely available and modifiable, promoting widespread adoption and customization. Despite these strengths, eSpeak's output often sounds robotic and artificial due to its formant-based approach, lacking the naturalness of neural text-to-speech systems like , which generate speech from human recordings or models. It exhibits limited capabilities in emotional intonation and expressive prosody, restricting its suitability for applications requiring nuanced vocal delivery. For non-English languages, synthesis accuracy depends heavily on rule-based conversion rules, which can result in approximations or errors in complex , particularly for languages with intricate or tonal features. In comparisons, eSpeak is more compact than the speech synthesis system, which offers greater expressiveness through diphone or unit selection methods but at the cost of higher resource requirements. However, it falls short in naturalness and emotional range compared to modern AI-driven synthesizers, making it particularly well-suited for tools, such as screen readers, rather than or high-fidelity audio production. User feedback highlights its clear enunciation even at elevated speeds, though potential artifacts may arise in handling intricate phonetic sequences. eSpeak NG's extensive multi-language support, covering over 100 languages and accents, further contributes to its versatility in diverse applications.

Synthesis Method

Text-to-Phoneme Conversion

eSpeak's text-to-phoneme conversion serves as the initial stage in its speech synthesis pipeline, transforming input text into a sequence of phonetic symbols that represent , including markers for stress and timing. This process relies on linguistic preprocessing to standardize the text and rule-based grapheme-to-phoneme (G2P) translation to map orthographic representations to phonemes, ensuring compatibility across supported languages. Preprocessing begins with text normalization, which handles elements such as abbreviations, numbers, and punctuation to convert them into a form suitable for phonemization. For instance, numbers are processed via the TranslateNumber() function, which constructs spoken forms from fragments based on language-specific options like langopts.numbers. Abbreviations and punctuation are addressed through replacement rules in the language's _rules file, such as the .replace section that standardizes characters (e.g., replacing special letters like ô or ő in certain languages). Tokenization occurs implicitly by breaking the text into words and applying rules or dictionary lookups word-by-word, preparing sequences for G2P matching. The core of the G2P conversion uses a combined with dictionaries for efficiency and accuracy. Rules, defined in files like en_rules for English, employ regex-like patterns to match letter sequences with context: <pre><match><post> <phonemes>, where <pre> and <post> provide surrounding context, and <match> identifies the to replace with . These rules are scored and prioritized, with the best match selected for conversion; for example, a rule might transform "b oo k" into the [U] for the "oo" in "". Dictionaries, stored in compiled files like en_dict, supplement rules with explicit entries for common or irregular words. The English , for instance, includes approximately 5,500 entries in its en_list file for precise pronunciations, such as "book bUk". For unknown words, the system falls back to algorithmic rules after checking for standard prefixes or suffixes, ensuring broad coverage. Language-specific rulesets are implemented through dedicated phoneme files (e.g., ph_english) and rule files, inheriting a base set of s while adding custom vowels, consonants, and translation logic tailored to the language's . Phonemes are represented using 1- to 4-character mnemonics based on the Kirshenbaum ASCII IPA scheme, allowing compact yet precise notation. Ambiguities in , such as stress placement and boundaries, are resolved using prosodic markers embedded in the output. Stress is assigned via symbols like &#36;1 for primary stress on the first or $u for unstressed , determined by entries or rule-based heuristics that analyze word structure. boundaries are implied through these markers and control from the base table, guiding the prosody for natural rhythm. The output of this stage is a stream of phonemes annotated with indicators and hints for duration and pitch, which feeds directly into subsequent synthesis processes to generate speech with appropriate intonation.

Formant Synthesis and Prosody

eSpeak utilizes synthesis to produce speech audio from sequences, modeling the human vocal tract through time-varying sine waves that represent the primary formants—typically the first three formants (F1 for vowel openness, F2 for front-back position, and F3 for additional spectral shaping)—while incorporating sources to simulate fricatives and other unvoiced sounds. This approach enables compact representation of multiple languages, as it relies on algorithmic generation rather than stored waveforms, resulting in clear output suitable for high-speed synthesis up to 500 . The core waveform creation follows a Klatt-style , employing a combination of cascade and parallel digital filters to shape an excitation signal—periodic pulses for voiced and random for unvoiced ones—into resonant formants that mimic natural speech spectra. Prosody in eSpeak is generated rule-based, applying intonation "tunes" to clauses determined by punctuation, such as a rising pitch contour for questions to convey interrogative intent or falling contours for statements. These contours are structured into components like the prehead (rising to the first stress), head (stressed syllables with modulated envelope), nucleus (peak stress with final pitch movement), and tail (declining unstressed endings), achieved by adjusting pitch envelopes on vowels within phoneme lists. Rhythm and emphasis are handled through duration scaling, where stressed syllables receive longer lengths than unstressed ones based on linguistic rules for syllable stress, influencing overall speech timing without altering the fundamental phoneme identities. For example, emphasis on a word increases its phoneme durations to highlight prosodic prominence. A key aspect of prosodic variation involves pitch modulation for smooth intonation transitions. This model allows dynamic adjustment of (F0) across utterances, with voice traits customizable via parameters such as base pitch (scaled 0-99, corresponding to approximately 100-300 Hz for typical male-to-female ranges), speaking speed (80-500 ), and for control (0-200, default 100). These settings enable users to tailor the synthetic voice for clarity or expressiveness while maintaining the synthesizer's efficiency.

Language Support

Coverage and Accents

eSpeak NG provides support for over 100 languages and accents. This extensive coverage includes major world languages such as English (with variants including American en-us, British en, en-029, and Scottish en-gb-scotland), Mandarin (cmn), Spanish (Spain es and Latin American es-419), French (France fr, fr-be, and fr-ch), (ar), and (hi). Regional accents and voices are achieved through customized mappings and prosody adjustments tailored to specific dialects, enabling variations like (pt-br) alongside standard (pt). The rule-based synthesis method facilitates this multi-language support in a compact form. Language data primarily derives from community-contributed rules developed by native speakers and contributors, which has enabled broad but uneven coverage across global linguistic families. Speech quality varies across languages, depending on the maturity of the rules and dictionaries, with support for languages like and Zulu. eSpeak NG continues to expand through ongoing community efforts, including enhancements to underrepresented languages such as additional African dialects in recent releases.

Customization and Extension

eSpeak NG allows users and developers to modify existing voices and add support for new languages or accents by editing plaintext data files, enabling customization without altering the core source code. Voices can be adjusted by editing phoneme definitions in files located in the phsource/phonemes directory, such as inheriting from a base table and specifying custom sounds for vowels, consonants, and stress patterns. Dictionaries, which handle text-to-phoneme (G2P) conversion, are modified in the dictsource/ directory through rule files (e.g., lang_rules) for general pronunciation patterns and exception lists (e.g., lang_list) for irregular words, allowing fine-tuning of accents like regional variations in English or French. To add a new , contributors create a voice file in espeak-ng-data/voices/ or espeak-ng-data/lang/ defining parameters such as pitch, speed, and prosody rules, alongside new and dictionary files tailored to the 's and . For tone languages or those with unique prosody, additional rules in the voice file adjust intonation and rhythm. The espeak-ng --compile=lang command compiles these changes into usable formats like phontab for and lang_dict for dictionaries; the functionality of the older espeakedit utility has been integrated into the espeak-ng program itself for command-line access. Integration with external dictionaries is possible by referencing custom rule sets during compilation. Best practices for customization emphasize starting with a rough based on similar existing languages, followed by iterative refinement through native speaker feedback to ensure natural and intonation. Testing involves running synthesized audio against sample texts using tools like make check or manual playback, with new unit tests added to the tests/ directory to verify stability across updates. Contributions, including modified voices or new languages, are submitted via pull requests to the eSpeak NG repository, where maintainers review and integrate them into official releases. Community efforts have extended eSpeak NG to constructed languages like through custom phoneme tables and rules capturing its phonetic regularity. Similarly, user-contributed improvements for Welsh include refined G2P rules for its mutations and , while ongoing work on Vietnamese has enhanced tone rendering via updated prosody parameters. These extensions demonstrate how the modular file structure facilitates broad participation in expanding eSpeak NG's capabilities.

Integrations and Applications

Platform Compatibility

eSpeak NG demonstrates broad platform compatibility as a lightweight, open-source speech synthesizer, supporting major desktop operating systems through standard build processes and audio interfaces. On Linux, it integrates seamlessly with audio systems such as ALSA and PulseAudio via the pcaudiolib library, enabling output on distributions like Ubuntu and Fedora. For Windows (requiring Windows 8.1 SDK or later), eSpeak NG utilizes DirectSound and WaveOut for audio playback, facilitating integration with screen readers and accessibility tools such as NVDA. On macOS, it is supported through ports available via package managers like MacPorts and Homebrew, using the same POSIX-compliant build tools as Linux. In mobile and embedded environments, eSpeak NG extends its reach to resource-constrained devices. Android support begins with API level 4.0 () and is available through native applications on the Store, as well as in terminal emulators like for command-line usage. For , an official eSpeak NG app has been available on the since September 2023, providing text-to-speech functionality on and devices. On embedded platforms like the , it operates natively under Raspbian or other variants, making it suitable for IoT applications due to its low resource footprint. Building eSpeak NG requires a C99-compliant such as GCC or , along with autotools for systems; Windows builds use or MSBuild (latest stable version 1.52.0 as of 2024). Cross-compilation is supported for embedded targets, allowing deployment on diverse hardware architectures, including ARM64. The synthesizer maintains minimal dependencies, relying solely on standard C libraries without external machine learning frameworks, which contributes to its portability across platforms. Optional libraries like pcaudiolib and Sonic handle audio processing and speed adjustments, but the core engine operates independently. This design ensures compatibility with a wide range of hardware and software configurations, from desktops to low-power IoT devices.

Notable Use Cases

eSpeak serves as the primary text-to-speech engine in the NVDA for Windows, providing essential audio feedback for visually impaired users since its integration in early versions of the software. This bundling enables NVDA to deliver multilingual without requiring additional installations, supporting over 100 languages and accents directly within the application. Similarly, eSpeak functions as the default for the on systems, facilitating accessible navigation of graphical interfaces through synthetic speech output. In telephony applications, eSpeak integrates with the open-source PBX via dedicated modules, allowing text-to-speech rendering for interactive voice responses and automated announcements in communication systems. For software development, Python bindings such as python-espeak enable developers to incorporate eSpeak into chatbots and virtual assistants, supporting offline voice output in custom applications. In educational contexts, eSpeak supports language learning tools by providing pronunciation guidance across numerous languages, aiding users in practicing and accents through its compact, formant-based synthesis. It is also embedded in e-book readers like , where it leverages system-level text-to-speech capabilities to read aloud content on and other platforms, enhancing accessibility for extended reading sessions. Recent adoptions include its continued use in OS for Chromebooks, with updates to the eSpeak-NG port ensuring compatibility and performance improvements as of 2024 releases. Additionally, open-source AI assistants like Mycroft utilize eSpeak NG for offline text-to-speech, allowing customizable voice parameters such as pitch and speed in privacy-focused environments. Overall, eSpeak's design and broad support have significant impact in low-resource settings, enabling speech access for visually impaired individuals in developing regions where high-end synthesizers are impractical due to its low computational requirements.

References

  1. https://espeak.sourceforge.net/
  2. https://github.com/espeak-ng/espeak-ng
  3. https://linuxcommandlibrary.com/man/espeak
  4. https://github.com/nvaccess/nvda/issues/5651
  5. https://sourceforge.net/p/espeak/mailman/espeak-general/
  6. https://github.com/espeak-ng/espeak-ng/releases/tag/1.50
  7. https://github.com/espeak-ng/espeak-ng/releases/tag/1.51
  8. https://github.com/espeak-ng/espeak-ng/releases/tag/1.52
  9. https://github.com/espeak-ng/espeak-ng/issues
  10. https://github.com/espeak-ng/espeak-ng/blob/master/docs/integration.md
  11. https://espeak.sourceforge.net/commands.html
  12. https://github.com/espeak-ng/espeak-ng/blob/master/COPYING
  13. https://medium.com/sciforce/text-to-speech-synthesis-an-overview-641c18fcd35f
  14. https://espeak.sourceforge.net/languages.html
  15. https://espeak.sourceforge.net/add_language.html
  16. https://lwn.net/Articles/190364/
  17. https://circuitdigest.com/microcontroller-projects/best-text-to-speech-tts-converter-for-raspberry-pi-espeak-festival-google-tts-pico-and-pyttsx3
  18. https://download.nvaccess.org/documentation/userGuide.html
  19. https://espeak.sourceforge.net/dictionary.html
  20. https://github.com/espeak-ng/espeak-ng/blob/master/dictsource/en_list
  21. https://espeak.sourceforge.net/phonemes.html
  22. http://www.kirshenbaum.net/IPA/ascii-ipa.pdf
  23. https://github.com/espeak-ng/klatt
  24. https://espeak.sourceforge.net/intonation.html
  25. https://github.com/espeak-ng/espeak-ng/issues/793
  26. https://www.cl.uzh.ch/dam/jcr:fbd23bb7-36e4-4eff-b2c7-ce549bd71d29/BIELAWSKI_Victor_BA_eSpeak-NG&Polish_HS22.pdf
  27. https://espeak.sourceforge.net/voices.html
  28. https://chromium.googlesource.com/chromiumos/third_party/espeak-ng/+/HEAD/docs/languages.md
  29. https://www.blog.brightcoding.dev/2025/09/12/espeak-ng-the-lightweight-open-source-voice-that-speaks-100-languages/
  30. https://chromium.googlesource.com/chromiumos/third_party/espeak-ng/+/HEAD/docs/add_language.md
  31. https://github.com/espeak-ng/espeak-ng/blob/master/docs/building.md
  32. https://ports.macports.org/port/espeak-ng/
  33. https://play.google.com/store/apps/details?id=com.redzoc.ramees.tts.espeak
  34. https://apps.apple.com/us/app/espeak-ng/id6444089174
  35. https://www.aranacorp.com/en/espeak-voice-synthesizer-on-raspberry-pi/
  36. https://github.com/espeak-ng/espeak-ng/releases
  37. https://docs.oracle.com/cd/E26502_01/html/E29026/ats-2.html
  38. https://zaf.github.io/Asterisk-eSpeak/
  39. https://pypi.org/project/python-espeak/
  40. https://fbreader.org/en/faq/tts
  41. https://chromium.googlesource.com/chromiumos/third_party/espeak-ng/
  42. https://mycroft-ai.gitbook.io/docs/using-mycroft-ai/customizations/tts-engine
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