Normal modes of vibration in balalaikas

Abstract

Using holographic interferometry, we have studied the vibrational behavior of a prima balalaika, a secondo balalaika, and an alto balalaika, all constructed at the Folk Musical Instrument Manufacturing Company in St. Petersburg, Russia. The modes of lowest frequency are characterized by the in-phase motion of the soundboard, while at higher frequencies we observe modes with longitudinal and transverse nodal lines where the soundboard pivots as it vibrates, much like the guitar. The modal frequencies are compared with the sound spectra recorded when the strings are plucked.