To provide a signal processing device and the like which are robust against contents of the input signal and noise, and can discard an input signal other than a specific category.

The signal processing device comprises: a detail degree determination section 5 for selecting a specific detail degree in which a feature characteristic of the input signal and a model become closest from a model 3 which expresses the feature characteristic of the signal belonging to the specific category, and which has a plurality of detail degrees; and a collating determination section 6 which determines that, when the specific detail degree is lower than a specific threshold value, it is not appropriate, and otherwise, it is appropriate, that the input signal is classified into the specific category.

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