To precisely detect abnormal sounds by an accident, etc., by collecting a sound signal emitted from a running car, and processing it.

The sound of a running car, generated from a sound source (a car being the object), is received by a sound input portion 102, is converted into a digital value by an analog-to-digital converter 103, and is stored in a memory portion 104 after that. The stored data is inputted into an FET processing portion 105 as single-frame data, after the passage of a predetermined time, and hear time frequency axis conversion processing is performed. After that, levels by bands are computed in a data-by-bands computing portion 106. Next, the level for all the bands is computed in an all-band level computing portion 107. After that, variations among a plurality of frames are computed in a plurality of frame data processing portion 108. On the basis of these data, abnormal sound determination is performed in a detection portion 109. Abnormal sound detection information 110 is outputted, when a sound is determined as an abnormal sound, here.