A mixed acoustic signal including sound emitted from a plurality of sound sources and sound source video signals representing at least one video of the plurality of sound sources are received as inputs, and at least a separated signal including a signal representing a target sound emitted from one sound source represented by the video is acquired. However, at least the separated signal is acquired using properties of the sound source that affects sound emitted by the sound source acquired from the video and/or features of a structure used for the sound source to emit the sound.