Apply a piano decay table to four per-partial envelopes and a recognisable hammered-string tone emerges from nothing but sine waves and timing.
In the world
A Steinway D's middle C has a fundamental that rings for five seconds, a 2nd harmonic that fades in three, and upper partials that are gone within one. The ratios were measured in the 1940s and have not changed since.
Here is an approximate piano decay table for the first four partials: 2.5 s, 1.6 s, 1.0 s, 0.6 s. Attack is a hard 3 ms on all four so they fire together, creating the characteristic bright strike. Apply these values to the four ADSRs on the rack and the patch will sound recognisably piano-ish.
Real pianos also include slight detune, sympathetic resonance, and hammer noise. Those are the next 10% of authenticity; the decay table is the first 60%.
Did you know?
A single piano note sets roughly 230 strings into sympathetic vibration. Even strings you did not strike resonate faintly through the bridge, adding a halo of overtones that no simple oscillator can replicate - this is why sampled pianos need gigabytes of data.
Explore
A giant vibrating string stretches across the 3D scene, showing standing wave modes rippling along its length. Click to strike it. Watch the higher modes (tighter ripple patterns) die out quickly while the fundamental keeps swinging - this is differential decay made visible, and it is exactly what makes a piano sound like a piano.