Harman Patil (Editor)

Speech recognition software for Linux

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There are currently several speech recognition software packages for Linux. Some of them are open-source while others are proprietary. Speech recognition usually refers to software that attempts to distinguish thousands of words in a human language. Voice control may refer to software used for sending operational commands to a computer.



In the late 1990s, a Linux version of ViaVoice (created by IBM) was made available to users for no charge. However, the free SDK was removed by the developer in 2002.

Current development status

Recently, there has been a push to get a high-quality native Linux speech recognition engine developed. As a result, numerous projects dedicated to creating Linux speech recognition solutions were established. One major hurdle is the compilation of a speech corpus to enable production of acoustic models. In response, VoxForge, which aims to collect transcribed speech for use with free and open-source speech recognition engines under the GPL license, was set up.

Speech recognition concept

The first step starts recording an audio stream on the linux machine. Then the user has two options:

  • process the voice recognition on his local machine or
  • submit the audio file to a remote server for converting the audio file into a text string.
  • The second option is used mainly on smartphones, because they do not have the performance and disk space to process the speech recognition on the phone.

    Free speech recognition engines

    The following is a list of current projects dedicated to implementing speech recognition in Linux, as well as major native solutions. These are not end-user applications. These are programming libraries that a programmer may use to develop an end-user application.

  • CMU Sphinx is a general term to describe a group of speech recognition systems developed at Carnegie Mellon University.
  • Julius is a high-performance, two-pass large vocabulary continuous speech recognition (LVCSR) decoder software for speech-related researchers and developers.
  • Kaldi a toolkit for speech recognition provided under the Apache licence.
  • Possibly Active Projects:

  • Speechpad.pw uses Google's speech recognition engine and Chrome native messaging API to provide direct speech input in Linux.
  • Speech uses Google's speech recognition engine to support dictation in many different languages.
  • Speech Control: is a Qt-based application that uses CMU Sphinx's tools like SphinxTrain and PocketSphinx to provide speech recognition utilities like desktop control, dictation and transcribing to the Linux desktop.
  • Platypus is an open source shim that will allow the proprietary Dragon NaturallySpeaking running under Wine to work with any Linux X11 application.
  • FreeSpeech, from the developer of Platypus, is a free and open source cross-platform desktop application for GTK that uses CMU Sphinx's tools to provide voice dictation, language learning, and editing in the style of Dragon NaturallySpeaking.
  • Vedics (Voice Enabled Desktop Interaction and Control System) is a speech assistant for GNOME Environment
  • GnomeVoiceControl is a dialogue system to control the GNOME Desktop that was developed in the Google Summer of Code in 2007.
  • NatI is a multi-language voice control system written in Python
  • SphinxKeys lets you essentially type keyboard keys and mouse clicks by speaking into your microphone. It's simple and works pretty much out of the box.
  • VoxForge is a free speech corpus and acoustic model repository for open source speech recognition engines.
  • Simon aims at being extremely flexible to compensate dialects or even speech impairments. It uses either HTK / Julius or CMU SPHINX, works on Windows and Linux and supports training.
  • Speeral Speeral a group of speech recognition tools developed at University of Avignon
  • Jasper project http://jasperproject.github.io/ Jasper is an open source platform for developing always-on, voice-controlled applications. This is an embedded Raspberry Pi front-end for CMU Sphinx or Julius
  • It is possible for developers to create Linux speech recognition software by using existing packages derived from open-source projects.

    Inactive Projects:

  • CVoiceControl is a KDE and X Window independent version of its predecessor KVoiceControl. The owner ceased development in alpha stage of development.
  • Open Mind Speech, a part of the Open Mind Initiative, aims to develop free (GPL) speech recognition tools and applications, as well as collect speech data. Production ended in 2000.
  • PerlBox is a perl based control and speech output. Development ended in early stages in 2004.
  • Xvoice A user application to provide dictation and command control to any X application. Development ended in 2009 during early project testing. (requires proprietary ViaVoice to function)
  • Proprietary speech recognition engines

  • Verbio ASR is a commercial speech recognition server for Linux and windows platforms.
  • DynaSpeak, from SRI International, (speaker-independent speech recognition software development kit that scales from small- to large-scale systems, for use in commercial, consumer, and military applications)
  • Janus Recognition Toolkit (JRTk) is a closed source speech recognition toolkit mainly targeted at Linux developed by the Interactive Systems Laboratories developed at Carnegie Mellon University and Karlsruhe Institute of Technology for which commercial and research licenses are available.
  • LumenVox Speech Engine is a commercial library for Linux and Windows for inclusion in other software. It has been integrated into the Asterisk private branch exchange system.
  • VoxSigma is a speech recognition software suite developed by Vocapia Research.
  • Voice control and keyboard shortcuts

    Speech recognition usually refers to software that attempts to distinguish thousands of words in a human language. Voice control may refer to software used for sending operational commands to a computer or appliance. Voice control typically requires a much smaller vocabulary and thus is much easier to implement.

    Simple software combined with keyboard shortcuts, have the earliest potential for practically accurate voice control in Linux.

    Using a compatibility layer

    It is possible to use programs such as Dragon NaturallySpeaking in Linux, by utilizing Wine, though some problems may arise, depending on which version is used.

    Using virtualized Windows

    It is also possible to use Windows speech recognition software under Linux. Using no-cost virtualization software, it is possible to run Windows and NaturallySpeaking under Linux. VMware Server or VirtualBox support copy and paste to/from a virtual machine, making dictated text easily transferable to/from the virtual machine.


    Speech recognition software for Linux Wikipedia

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