Analysis of Broadband Directivity and FFT Response across One-Third Octave Bands for a Yaybahar vs a Cello

This paper presents an exploration of the Yaybahar, a unique stringed instrument invented by Gorkem Sen. The Yaybahar replaces the resonating body typically found in stringed instruments with a “Thunder Drum” assembly, a combination of a spring and membrane system that enhances the acoustic amplification of the instrument. The excitation of the strings is transmitted through the spring into the membrane, amplifying the output signal and augmenting the sound of the strings with a unique reverb. This results in an acoustics synthesizer that offers multiple avenues for playing, including the strings, spring, and frame drum. The aim of this study is to compare the acoustical properties of the Yaybahar with the long-established Cello to shed light on the instrument. The study focuses on comparative analysis of both the musical instruments through spectral, directivity, Fourier Frequency Transform (FFT) response and vibration transmission analysis. Despite its complex appearance, the Yaybahar is a highly expressive instrument. This paper focuses on Directionality and FFT analysis. Preliminary findings suggest that while the Yaybahar’s sound pressure levels across the frequency spectrum are lower than those of a Cello, it exhibits a similar but a stronger harmonic response. Further research is proposed to understand the behavior of springs in signal transmission/amplification and to investigate how structural integrity can sustain a note longer when the strings are plucked. Additionally, a deeper examination of the Yaybahar’s dimensions and configuration may enable higher sound pressure levels. Future work will also explore the relationship of string thickness and tuning against the steel gauge of the springs, its diameter, the membrane material, frame diameter and tuning. This will contribute to the existing knowledge about the instrument and may also provide insights into the harmonics of the spring and membrane.