Audio block detector

PURPOSE: To provide the audio block detector which prevents a non-audio block from being erroneously recognized as an audio block even when the revolving speed of an engine considerably changes and the feature pattern of an input signal considerably changes. CONSTITUTION: An engine revolving speed measuring part 11 measures the revolving speed of an engine for the unit of a frame having a fixed time length, and an engine revolving speed calculating part 12 calculates the average engine revolving speed of a noise block corresponding to the engine revolving speed. Then, an engine revolving speed change judge part 31 judges whether the engine revolving speed has changed or not from the engine revolving speed, average engine revolving speed and threshold value for judging the change of the engine revolving speed and judges whether the input signal is sounded or not for each frame corresponding to an inter-pattern distance between the feature pattern of the input signal and a standard noise pattern and when the time length of the block where the change of the engine revolving speed from the average engine revolving speed is larger than the prescribed threshold value is longer than a prescribed rate, such a block is not recognized as the audio block by an audio block judge part 41. COPYRIGHT: (C)1993,JPO&Japio