DtmfRecognitionEngine Class

Provides access to DTMF recognition services.

Inheritance Hierarchy


Namespace:  Microsoft.Speech.Recognition
Assembly:  Microsoft.Speech (in Microsoft.Speech.dll)


Public Class DtmfRecognitionEngine _
    Implements IDisposable
Dim instance As DtmfRecognitionEngine
public class DtmfRecognitionEngine : IDisposable


Dual-Tone Multi-Frequency (DTMF) tones are generated by pressing the keys on a telephone. The DtmfRecognitionEngine class supports the use of speech recognition grammars to analyze DTMF input emitted by telephones. The members of DtmfRecognitionEngine are similar to those of the SpeechRecognitionEngine class. However, the input for recognition consists of a series of DTMF tones instead of an audio stream.

The DtmfRecognitionEngine works by performing a series of emulated recognitions. It maintains a buffer with a list of tones that have been received. Every time a new tone is received, it appends the new tone to the list and emulates recognition of the whole list. This process continues until emulation produces a definitive result, or one of the timeouts is reached.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also


DtmfRecognitionEngine Members

Microsoft.Speech.Recognition Namespace