Damping the strings of a guitar with the side of the hand.
Damping is the quieting or silencing of the strings of an instrument after they have been played. More generally, the suppression of vibrations using an electrical or mechanical device. Sometimes called dampening or choking.
More generally, in acoustics, damping is the loss or dissipation of the oscillatory or vibrational energy of an electrical or mechanical system. See also acoustic absorption.