Speech grammars example
I figured it's about time for another example.
A lot of scenarios require the speech recognizer to listen for a constrained set of phrases - a "grammar". The app developer can express this with the W3C's SRGS XML format. The WinFX speech API provides a set of classes for producing an SRGS grammar document. (SRGS = "Speech Recognition Grammar Specification", and you can read all about it at the W3C)
So here's an example of a grammar that recognizes simple algebraic statements like "3 x y", "7 x", "4 y".
Function MathGrammar() As SrgsDocument
'create a one-of to detect the numbers 1 through 10
Dim numberOneOf As New SrgsOneOf
Dim i As Integer
For i = 1 To 10
numberOneOf.Add(New SrgsItem(i.ToString))
Next
'wrap this in an optional item
Dim numberItem As New SrgsItem
numberItem.Add(numberOneOf)
numberItem.SetRepeat(0, 1)
'create a one-of to detect "x" and "y"
Dim variableOneOf As New SrgsOneOf("x", "y")
'wrap this in an optional item
Dim variableItem1 As New SrgsItem
variableItem1.Add(variableOneOf)
variableItem1.SetRepeat(0, 1)
'and again, in a second optional item
Dim variableItem2 As New SrgsItem
variableItem2.Add(variableOneOf)
variableItem2.SetRepeat(0, 1)
'string the three items together into a rule
Dim productRule As New SrgsRule("product")
productRule.Add(numberItem)
productRule.Add(variableItem1)
productRule.Add(variableItem2)
'put the rule into an srgs document
Dim srgs As New SrgsDocument
srgs.Rules.Add(productRule)
srgs.Root = productRule
MathGrammar = srgs
End Function
One thing to note about this is that I'm adding numerals, but the underlying recognizer will normalize this into words. So, although the grammar contains the character "7", the recognizer listens for "seven".
If you want to paste this into an app to see what happens, here's the rest of the code:
Imports
System.Speech.GrammarBuilding
Imports
System.Speech.Recognition
Public
Class Form1
Dim WithEvents reco As New DesktopRecognizer
'insert MathGrammar function here
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
reco.LoadGrammar(New Grammar(MathGrammar()))
End Sub
Private Sub reco_SpeechRecognized(ByVal sender As Object, ByVal e As System.Speech.Recognition.RecognitionEventArgs) Handles reco.SpeechRecognized
Me.Text = e.Result.Text
End Sub
End
Class
(Don't forget to add the reference to Speech to your project.)
Hope this is helpful.
Cheers,
/Rob
