Key used to retrieve a float array from the Android.OS.Bundle passed to the IRecognitionListener.OnResults(Android.OS.Bundle) and IRecognitionListener.OnPartialResults(Android.OS.Bundle) methods. The array should be the same size as the ArrayList provided in SpeechRecognizer.ResultsRecognition, and should contain values ranging from 0.0 to 1.0, or -1 to represent an unavailable confidence score.
Confidence values close to 1.0 indicate high confidence (the speech recognizer is confident that the recognition result is correct), while values close to 0.0 indicate low confidence.
This value is optional and might not be provided.