RecognizedWordUnit.Confidence Property


Gets a value, assigned by the recognizer, that represents the likelihood that a recognized word matches a given input.

 property float Confidence { float get(); };
public float Confidence { get; }
member this.Confidence : single
Public ReadOnly Property Confidence As Single

Property Value


A relative measure of the certainty of correct recognition for a word. The value is from 0.0 to 1.0, for low to high confidence, respectively.


Confidence scores do not indicate the absolute likelihood that a word was recognized correctly. Instead, confidence scores provide a mechanism for comparing the relative accuracy of multiple recognition alternates for a given input. This facilitates returning the most accurate recognition result. For example, if a recognized word has a confidence score of 0.8, this does not mean that the word has an 80% chance of being the correct match for the input. It means that the word is more likely to be the correct match for the input than other results that have confidence scores less than 0.8.

A confidence score on its own is not meaningful unless you have alternative results to compare against, either from the same recognition operation or from previous recognitions of the same input.

The values returned by Confidence are relative and unique to each recognition engine. There is no definition of how confidence values between two different recognition engines compare, nor how the Confidence of individual RecognizedWordUnit objects define the Confidence of a RecognizedPhrase.

A speech recognition engine may assign a low confidence score to spoken input for various reasons, including background interference, inarticulate speech, or unanticipated words or word sequences. If your application is using a SpeechRecognitionEngine instance, you can modify the confidence level at which speech input is accepted or rejected with one of the UpdateRecognizerSetting methods. Confidence thresholds for the shared recognizer, managed by SpeechRecognizer, are associated with a user profile and stored in the Windows registry. Applications should not write changes to the registry for the properties of the shared recognizer.

Applies to