knocks — to strike a sounding blow with the fist, knuckles, or anything hard, especially on a door, window, or the like, as in seeking admittance, calling attention, or giving a signal: to knock on the door before entering.
drums — a musical percussion instrument consisting of a hollow, usually cylindrical, body covered at one or both ends with a tightly stretched membrane, or head, which is struck with the hand, a stick, or a pair of sticks, and typically produces a booming, tapping, or hollow sound.
