A filter includes a multilayer body including a plurality of insulator layers stacked on top of one another. In the board, there are provided a board opening portion that is formed to face the diaphragm and locating walls that come in contact with the electroacoustic conversion portion to locate the electroacoustic conversion portion. 5 degree of polymerization identical to that of the natural molecule, that is 20 to 30. With this operation, the temperature state of the vehicle cabin from the start of the pre-air-conditioning can be properly communicated to a vehicle user.