A Dialog Manager is one component of a Speech Recognition System.

Telephony and Command & Control Dialog Managers

A Dialog Manager used in Telephony applications (IVR - Interactive Voice Response), and in some desktop Command and Control Application, assigns meaning to the words recognized by the Speech Recognition Engine, determines how the utterance fits into the dialog spoken so far,and decides what to do next.  It might need to retrieve information from an external source.  If a response to the user is required, it will choose the words and phrases to be used in its response to the user, and transmit these to the Text-to-Speech System to speak the response to the user.

Dictation Dialog Manager 

A Dictation Dialog Manager will typically take the words recognized by the Speech Recognition Engine and type out the corresponding text on your computer screen.  It may also have some Command and Control elements, but these are usually limited to the types of commands typically used in a word processing program.  It usually responds to the user using text (i.e. it might not use Text to Speech to respond to the user).

Examples 

Examples of Telephony Dialog Managers include: 

• Ravenclaw,
• jvoicexml,
• ariadne, or
• jaspis. 

An example of a Command & Control Dialog Manager:

• Gnome-Voice-Control  (uses PocketSphinx)
• SpeechLion (uses Sphinx4)
  
• PerlBox (uses Sphinx2)
• Simon (uses Julius)

An example of a Dictation Dialog Manager, with Command & Control elements, would be:

• xVoice (needs IBM's ViaVoice engine for Linux - no longer available)
• Evaldictator (uses Sphinx4)

You can also write a domain specific application to perform Dialog Manager-like tasks using a traditional programming language (C, C++, Java, etc.) or a scripting Language (Perl, Python, Ruby, etc.).