To construct a natural and comfortable sound field in a vehicle with a simple constitution.

A vibrating member 20 is arranged in the vicinity of a vehicle inside wall 12 for forming the vehicle inside 11. A microphone 40 for vehicle inside voice is arranged inside the vehicle inside wall (a space in the outside direction of the vehicle inside wall more than the vibrating member), and a microphone 45 for passing voice is arranged outside the vehicle inside wall (the space in the outside direction of the vehicle inside wall more than the vibrating member), respectively. For forming a vehicle inside signal of collecting a sound by the microphone for the vehicle inside voice as a voice signal having the desired acoustic effect in a signal processing part 50, a characteristic of the passing voice of collecting the sound by the microphone for the passing voice and an acoustic characteristic of the vibrating member are added, and a vibration waveform is generated for sending out echo voice in the vibrating member to a space in the inside direction of the vehicle inside wall. An acoustic effect in the vehicle is realized by generating the echo voice by imparting vibration of the vibration waveform generated by the signal processing part to the vibrating member from a piezoelectric vibrating element 30 arranged in the vibrating member.