Patent ID: 7991614
Filing Date: 2011-08-02
Classification: G10L

Abstract:
1. A speech recognition system implemented by a processor comprising: a feature calculating unit that converts, by the processor, an input sound signal into a feature for each frame; a sound level calculating unit that calculates, by the processor, an input sound level expressed as either power of the sound signal in each frame or logarithm of the power or an amplitude of the sound signal in each frame or logarithm of the amplitude; a decoding unit that receives the feature of each frame calculated by the feature calculating unit, matches, by the processor, the feature with an acoustic model and a linguistic model recorded in advance, and determines a recognized word sequence to be output based on the matching results, the acoustic model being data obtained by modeling of what feature speech is likely to have, and the linguistic model being data relating to a recognition word; a start-point detector that compares, by the processor, the input sound level calculated by the sound level calculating unit with a reference value to determine a start frame serving as a start point of a speech section and notifies the decoding unit of the start frame; an end-point detector that compares, by the processor, the input sound level calculated by the sound level calculating unit with a reference value to determine an end frame serving as an end point of the speech section and notifies the decoding unit of the end frame; and a reference value updating unit that updates, by the processor, the reference value in accordance with variations in the input sound level after the start frame, wherein when the reference value updating unit updates the reference value, the start-point detector updates the start frame using the updated reference value and notifies the decoding unit of the updated start frame, and when the decoding unit starts matching the feature with the acoustic model and the linguistic model and then is notified of the updated start frame from the start-point detector after starting the matching and before being notified of the end frame from the end-point detector, the decoding unit corrects the already existing matching results of the decoding unit in accordance with the notified updated start frame.