Method, apparatus, and medium for measuring confidence about speech recognition in speech recognizer

A method of measuring confidence of speech recognition of a speech recognizer, the method comprising:

• extracting a feature of a speech signal;
• calculating a spectrogram of the speech signal;
• recognizing a speech from the extracted feature of the speech signal by using a predetermined speech recognition model;
• comparing a phase change of the speech signal by using a result of speech recognition and the calculated spectrogram;
• calculating a likelihood ratio of the speech recognition according to the speech recognition model;
• and
• calculating confidence of the speech recognition by considering the phase change comparison and the likelihood ratio.

A measuring apparatus for confidence of speech recognition in a speech recognizer, the apparatus comprising:

• a phase change detection unit detecting a phase change point of a speech signal;
• a phoneme string change detection unit detecting a phoneme string change point according to a result of speech recognition in the speech recognizer;
• and
• a confidence calculation unit calculating confidence of the speech recognition by using a comparison result a detected phase change point with the detected phoneme string change point, and a likelihood ratio.

A measuring apparatus of confidence of speech recognition in a speech recognizer, the apparatus comprising:

• a feature extraction unit extracting a feature of a speech signal;
• a spectrogram calculation unit calculating a spectrogram of the speech signal;
• a speech recognition unit recognizing a speech from a feature of the extracted speech signal by using a predetermined speech recognition model;
• a phase change comparison unit comparing phase changes of a speech signal by using a result of speech recognition and the calculated spectrogram;
• a likelihood ratio calculation unit calculating a likelihood ratio of the speech recognition according to the result of speech recognition;
• and
• a confidence measuring unit calculating confidence of the speech recognition by considering both the comparison result of the phase change and the likelihood ratio.