ACCIDENT SOUND DETECTION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide an accident sound detection circuit improved in the detecting ability of accident sound by enabling the discrimination of a sudden brake sound from a siren. SOLUTION: This detection circuit comprises an accident sound reading means 10 for extracting a prescribed signal component having a prescribed level or more of fluctuation of signal level from a voice signal of traffic sound; a pitch fluctuation determination arithmetic means 30 for determining the magnitude of fluctuation ratio of a basic frequency based on the prescribed signal component; and a pitch fluctuation sound removing means 20 for removing the prescribed signal component when the fluctuation ratio is larger than a prescribed fluctuation ratio, and outputting the prescribed signal component as the accident sound when the fluctuation ratio is the prescribed fluctuation ratio or less. The pitch fluctuation determination arithmetic means 30 includes a wavelet conversion arithmetic means 31 for wavelet-transforming the prescribed signal component at prescribed intervals; a pitch arithmetic means 32 for calculating the basic frequency between peaks of a prescribed value or more; and a pitch fluctuation determination means 33 for comparing the prescribed fluctuation ratio with the fluctuation ratio of the basic frequency to determine the magnitude of the fluctuation ratio. COPYRIGHT: (C)2004,JPO