Microphone array measurements, high-speed camera recordings, and geometrical finite-differences physical modeling of the grand piano

Abstract

Microphone array measurements of a grand piano soundboard show similarities and differences between eigenmodes and forced oscillation patterns when playing notes on the instrument. During transients the driving point of the string shows enhanced energy radiation, still not as prominent as with the harpsichord. Lower frequencies are radiated stronger on the larger side of the soundboard wing shape, while higher frequencies are radiated stronger on the smaller side. A separate region at the larger part of the wing shape, caused by geometrical boundary conditions has a distinctly separate radiation behavior. High-speed camera recordings of the strings show energy transfer between strings of the same note. In physical models including hammer, strings, bridge, and soundboard the hammer movement is crucially necessary to produce a typical piano sound. Different bridge designs and bridge models are compared enhancing inharmonic sound components due to longitudinal-transversal coupling of the strings at the bridge.