A signal processing device comprising: a sound collection signal input unit configured to input sound collection signals of a sound collection unit that collects a sound produced by a user with a plurality of microphones disposed to surround the user in a reproduction environment and forming a first closed surface, each sound collection signal is collected by a respective one of the microphones; a sound emission control unit configured to receive an output signal and cause a plurality of speakers to emit a sound based on the output signal, the speakers being disposed to surround the user in the reproduction environment and forming a second closed surface; and an acoustic signal processing unit configured to perform on the sound collection signals from the sound collection signal unit a first acoustic signal process by applying on the sound collection signals first transfer functions for reproducing a sound field in which the sound produced by the user can be sensed by the user as if the sound were echoing in a specified place, thereby generating the output signal, wherein the first transfer functions are measured in the specified place to indicate how a sound emitted from the first closed surface surrounding the user inside the specified place echoes in the specified place and then is transferred to the second closed surface, characterized by: an operation unit configured to allow the user to designate a position information, wherein the specified place is specified from the designated position information; and a display control unit configured to cause a display unit to display an image that corresponds to the specified place, wherein the acoustic signal processing unit is configured to add a reference sound to each of the sound collection signals before they undergo the first acoustic signal process, the reference sound being pre-prepared sound data which are a collected sound or an artificial sound. a sound collection signal input unit configured to input sound collection signals of a sound collection unit that collects a sound produced by a user with a plurality of microphones disposed to surround the user in a reproduction environment and forming a first closed surface, each sound collection signal is collected by a respective one of the microphones; a sound emission control unit configured to receive an output signal and cause a plurality of speakers to emit a sound based on the output signal, the speakers being disposed to surround the user in the reproduction environment and forming a second closed surface; and an acoustic signal processing unit configured to perform on the sound collection signals from the sound collection signal unit a first acoustic signal process by applying on the sound collection signals first transfer functions for reproducing a sound field in which the sound produced by the user can be sensed by the user as if the sound were echoing in a specified place, thereby generating the output signal, wherein the first transfer functions are measured in the specified place to indicate how a sound emitted from the first closed surface surrounding the user inside the specified place echoes in the specified place and then is transferred to the second closed surface, characterized by: an operation unit configured to allow the user to designate a position information, wherein the specified place is specified from the designated position information; and a display control unit configured to cause a display unit to display an image that corresponds to the specified place, an operation unit configured to allow the user to designate a position information, wherein the specified place is specified from the designated position information; and a display control unit configured to cause a display unit to display an image that corresponds to the specified place, wherein the acoustic signal processing unit is configured to add a reference sound to each of the sound collection signals before they undergo the first acoustic signal process, the reference sound being pre-prepared sound data which are a collected sound or an artificial sound.