A piano soundboard conserves and recycles vibrational energy through repeated edge reflections

Evidence

Low internal friction in the board and big impedance mismatches at its clamped edges on the heavy piano frame means the board wastes little energy. Energy that reaches an edge gets reflected with little loss. A hammer tap on a piano soundboard is far from a dull thud. The tap echoes many times—that is, the bending wave energy reflects off a succession of clamped edges and returns to the point of the tap in thousands of different ways before the energy dies out. The multiple reflections keep the energy confined to the small space of the soundboard, where it is available to radiate as sound. — Eric J. Heller, Why You Hear What You Hear- An…, 1167