Pianos use multiple strings per note to improve energy transfer and loudness

Evidence

The hammer is heavy and it can impart more total energy to three strings than to one, which because of their added mass and inertia are a better impedance match to the hammer. … Although a heavier, thicker wire could also be used to increase mass, its inharmonicity would be unacceptably high. … The heavier mass of the three strings also means a better impedance match at the bridge—so the note will be louder, especially in the first moments when all three strings are in phase. (Our impression of loudness comes more from the strike and less from the decay.) — Eric J. Heller, Why You Hear What You Hear- An…, 1830

Categorization

• XREF: Connects to the impedance-matching and energy-transfer mechanics theme from Chapter 19’s broader physics-of-instruments thread; ties to how instruments couple to their resonators.