vibrations

vi*bra*tion

noun

{bc}a periodic motion of the particles of an elastic body or medium in alternately opposite directions from the position of equilibrium when that equilibrium has been disturbed (as when a stretched cord produces musical tones or molecules in the air transmit sounds to the ear)

sympathetic vibration

noun

{bc}a vibration produced in one body by the vibrations of exactly the same period in a neighboring body