Provided is a signal processing device including a display control unit for causing a display to display an image corresponding to a specified place, a sound-collection-signal input unit for inputting a sound collection signal of a sound collection unit that collects a user sound produced with microphones surrounding the user, an acoustic-signal processing unit for performing a first acoustic-signal process for reproducing a sound field where the user sound is sensed as if the sound were echoing in the place on the signal input by the sound-collection-signal input unit, based on a first transfer function measured in the place to indicate how a sound emitted on a closed surface inside the place echoes in the place and then is transferred to the closed-surface side, and a sound-emission control unit for causing a sound based on the processed signal to be emitted from speakers surrounding the user.