CMUSphinx Documentation

This page contains collaboratively developed documentation for the CMU Sphinx speech recognition engines.

Beginner User Documentation

This section contains links to documents which describe how to use Sphinx to recognize speech. Currently, we have very little in the way of end-user tools, so it may be a bit sparse for the forseeable future.

You are in trouble - read the FAQ

See also some more docs:

If you want to find out where CMUSphinx works, see

Advanced User Documentation

These documents either describe some particular aspect of the Sphinx codebase in detail, or they serve as a developer’s guide to accomplishing some particular task.

How To Contribute

Please consider project ideas ProjectIdeas, some of them are easy, some harder. If you want to start work on any of them, please let us know.


These documents describe the excruciating detail of APIs, or provide other useful background information for CMUSphinx developers.

Developer Documentation

This section contains various internal information for CMUSphinx developers. But we hope it will be still usable for you.

File formats

Data sources

Available data sources are covered on the page SpeechData

Speech Recognition Theory

This section tries to collect research ideas for specific problems in speech recognition