Vibration and sound radiation of a piano soundboard

Abstract

Vibration and radiation characteristics of a piano soundboard for a 6-ft grand piano are investigated by use of modal analysis and surface-intensity methods. The mode shapes and frequencies of six resonances below 200 Hz are shown, and their relations to intensity patterns are discussed. The intensity pattern changes in a very complex manner as the frequency varies. The radiation efficiency below 80 Hz is very low. Sound is radiated fairly efficiently in the frequency range of 100 Hz–1 kHz, and very efficiently above 1.4 kHz. The results indicate that it is very important to make the input power to the soundboard as constant as possible with respect to the driving point as well as the driving frequency, in order to achieve a smooth change of sound power output from note to note.