Piano string excitation: The question of gravity influence on the sound spectra
Anatoli Stulov · The Journal of the Acoustical Society of America · 1999
The influence of gravity on the process of the grand piano hammer–string interaction was appreciated by D. E. Hall [J. Acoust. Soc. Am. 79, 141–147 (1986)]. Using the reasonable physical assumptions, it was shown that the gravity influence is small and may not be taken into account. It is obvious, but it is important to know exactly what this influence is. The vibration spectra of different flexible strings excited by piano hammers in the gravity field and without gravity were analyzed here. Of course, the influence of gravity increases with the increasing of the contact time. Its depends on the hammer velocity; therefore, the string excitation by hammers with velocities less than 0.5 m/s was considered. It was shown that: the gravity influence is greater for the smooth hammers, and this influence is more essential for the middle range of notes; for the small velocities of hammers the gravity changes the mode energy levels of the primary harmonics up to 10 dB, if the hammer strikes only one string of the triple set; the gravity must be taken into account definitely, if the contact time is greater than 5 ms.