Method and apparatus of confidence measure calculation

A confidence measure calculation apparatus that calculates a confidence measure of a target word string specified in a recognition result, the apparatus comprising:

• a generator generating an alternative candidate word string in a position of the target word string;
• a training unit training a classifier which is configured to discriminate between the target word string and the alternative candidate word string;
• an extractor extracting a feature value representing an adjacent context in the position of the target word string;
• and
• a calculator determining whether a true word string in the position of the target word string is the target word string or the alternative candidate word string by using the classifier and the feature value, and calculating a confidence measure of the target word string on the basis of the determination result.

A confidence measure calculation apparatus that calculates a confidence measure of a target word string specified in a recognition result, the apparatus comprising:

• means for generating an alternative candidate word string in a position of the target word string;
• means for training a classifier which is configured to discriminate between the target word string and the alternative candidate word string;
• means for extracting a feature value representing an adjacent context in the position of the target word string;
• and
• means for determining whether a true word string in the position of the target word string is the target word string or the alternative candidate word string by using the classifier and the feature value to calculate a confidence measure of the target word string on the basis of the determination result.

A non-transitory computer-readable recoding medium that stores a program which causes a computer to execute the processes of:

• receiving a recognition result and a target word string which is specified in the recognition result;
• generating an alternative candidate word string in a position of the target word string;
• training a classifier which is configured to discriminate between the target word string and the alternative candidate word string;
• extracting a feature value representing an adjacent context in the position of the target word string;
• determining whether a true word string in the position of the target word string is the target word string or the alternative candidate word string by using the classifier and the feature value;
• and
• calculating a confidence measure of the target word string on the basis of the determination result.