Evaluation of a digital grand piano for vibrotactile feedback experiments and impact of finger touch on piano key vibrations

Pianists usually pay little attention to piano key vibrations but it was shown that they influence the perceived quality of an instrument and it was suggested that they might play a role for the precise timing and dynamic control in piano playing. To objectively measure and understand the influence of vibrotactile feedback in the pianist-piano interaction, we plan experiments with a digital hybrid grand piano - the Yamaha AvantGrand N3X - that simulates piano key vibrations with a rendering system. In this paper, we evaluate piano key vibrations of this instrument with a laser Doppler vibrometer and compare the vibrations to measurements with an acoustic grand piano. The peak levels of both instruments (13 to 35 μm for the acoustic grand piano and 16 to 25 μm for the AvantGrand) are comparable but the rendering system has limitations outside the frequency range from 150 to 400 Hz. Furthermore, the perceptibility of the vibrations at the left and right hand playing positions is investigated. Finally, the impact of the finger on the vibrations during different stages of a key press is analyzed and it is demonstrated that the finger influences the displacement levels and the spectral weighting of the piano key vibrations.