Abstract: An apparatus adopting an iron core and an inertial mass is disclosed for exerting high power output by converting a sound signal to vibration so as to stimulate the human hearing organs through the bones. A sound-to-vibration conversion apparatus comprises a housing, a permanent magnet having an N-pole and an S-pole, only one pole of which is fixed to the housing, an electromagnet movably installed into the housing faced either the S-pole or N-pole of the permanent magnet, whichever one is not fixed to the housing, and an inertial mass for amplifying the inertial force of reciprocating movement of the electromagnet, so that the housing with the permanent magnet can be vibrated by the electromagnet, whereby the electromagnet vibrates in a reciprocating fashion towards or away from the permanent magnet in accordance with the incubation between the polarity formed at the electromagnet by acoustic signal applied to the electromagnet and either the N-pole or the S-pole of the permanent magnet.