Abstract: Cylindrical ventilation ports radiating sound radiated from a rear surface of a diaphragm to an outside are projected from a rear surface of the electroacoustic converter having the diaphragm inside. A distal end of each ventilation port is located in a through hole of a circuit board, on which the electroacoustic converter is mounted, at a position farther away from the diaphragm than a contact surface of the circuit board. The distal end of each ventilation port may be in the through hole or may be protruded to the outside from the rear surface of the circuit board. As a result, since separation from the radiated sound from the front surface of the diaphragm is achieved, the radiated sound from the rear surface of the diaphragm is prevented from interfering with the radiated sound from the front surface of the diaphragm.

Abstract: Cylindrical ventilation ports radiating sound radiated from a rear surface of a diaphragm to an outside are projected from a rear surface of the electroacoustic converter having the diaphragm inside. A distal end of each ventilation port is located in a through hole of a circuit board, on which the electroacoustic converter is mounted, at a position farther away from the diaphragm than a contact surface of the circuit board. The distal end of each ventilation port may be in the through hole or may be protruded to the outside from the rear surface of the circuit board. As a result, since separation from the radiated sound from the front surface of the diaphragm is achieved, the radiated sound from the rear surface of the diaphragm is prevented from interfering with the radiated sound from the front surface of the diaphragm.