The Variation in the Acoustic Response of the Karadeniz Kemenche Depending on the Thickness of the Soundboard

Abstract

The variation in the acoustic response of the Karadeniz kemenche, a bowed string musical instrument, depending on the thickness of the soundboard is investigated. The most important challenge in obtaining an updated model for the musical instruments is the uncertainties arising from the orthotropic wood materials used. A model update procedure is implemented to resolve uncertainties in the mechanical properties of materials. The model is updated and complemented through an experimental modal analysis study. An analytical solution for the calculation of acoustic mode frequencies is implemented. A vibroacoustic analysis is performed to model the fluid–structure interaction. An acoustic response analysis is conducted by applying the experimentally measured nonlinear triaxial acceleration signal to the bridge of the musical instrument to simulate the slip–stick behaviour of the bow. Finally, the effect of soundboard thickness on the amplitude of acoustic pressure is examined. It is revealed that the amplitude of acoustic pressure substantially increases at the resonances that appeared at 340 Hz and 900 Hz, when the thickness of soundboard is 2.1 mm, and the amplitudes of pitch frequencies are observed to be higher in a broadband range. When the thickness of the soundboard of the instrument is 1.7 mm, it is seen that the amplitude of the pitch frequency of 1040 Hz increases significantly, and thus, it can produce a higher-pitched sound. When the soundboard thickness of the instrument is 2.9 mm, a strong pitch frequency of around 700 Hz can be obtained, according to the results of the studied model.