Phantom partials in the piano sound and the role of the soundboard
Eric Rokni, Camille Adkison, Thomas R. Moore · The Journal of the Acoustical Society of America · 2017
The presence of phantom partials in the spectra of the piano sound are well known, and for decades they have been attributed to forced longitudinal vibrations in the string. These vibrations are generally assumed to originate with the stretching of the string, which produces frequency components at the sums, differences and second harmonics of the resonant frequencies of the transverse string motion. Results of recent experiments indicate that phantom partials can be produced in other parts of the piano as well as the string, and in some cases these contributions to the sound can be significant. Measurements of the power in multiple phantom partials produced simultaneously by steady-state excitation are providing insight into the process that creates them.