To appropriately recover a dynamic range of an acoustic signal.

An expansion section detection device 112 detects a center localization degree indicating a degree of concentration on a center of a localization distribution of a corrected input signal having a level corrected by an AGC 111, and on the basis of the center localization degree, detects an expansion section where a dynamic range of the input signal is to be expanded. A dynamic range expander 115 expands the dynamic range of the corrected input signal in the expansion section. The present invention is applicable, for example, to a music player.