A string vibration sustaining device according to the present embodiment includes a rear pickup converting string vibration into an electrical signal, an amplifier amplifying the converted electrical signal, and an ultrathin electromagnetic driver converting the amplified electrical signal into a magnetic signal to excite strings. The t vertical web or webs and isare provided between the first and second longitudinal seams. Similarly, the upper armature is further operable to absorb energy generated at the thoracic region to activate the headrest following the initial response by the lower armature.