A Speech Recognition Grammar sets out all the acceptable words and phrases that a user might say at a particular point in a dialog with a Speech Recognition System. A Grammar file is used in Desktop Command & Control or Telephony IVR (Interactive Voice Response) Speech Recognition applications.
A simple grammar (in HTK format) might look like the following:
$name = [ STEVE ] YOUNG| [JOHN] DOE;
( START (PHONE|CALL) $name) END )
Basically this tells the Speech Recognition Engine to recognize the following utterances (note that the vertical bar in the grammar denotes 'or', and the contents of a set of square brackets indicates an optional utterance):
Any other utterance is ignored by the Speech Recognition Engine, which usually returns an 'out of grammar' error. So the following utterances would be rejected by the Speech Recognition Engine:
For additional information, see these links: