Sound producing device for use in vehicle i.e. railway train, has electrostatic surface transmitter provided in walls of compartment and invisibly arranged behind lining of walls, where walls or part of walls is component of transmitter

摘要

The device has an electrostatic surface transmitter provided in walls of a compartment of a vehicle i.e. railway train. The electrostatic surface transmitter is invisibly arranged behind a lining of the walls. The walls or a part of the walls is a component of the electrostatic surface transmitter. The electrostatic surface transmitter has a diaphragm that vibrates for producing sound, where the diaphragm is attached to stator structures. The diaphragm provides phase-coherent vibration that converts an electrical input signal into acoustic planar waves.