Operational Modal Analysis of Singing Bowls

Ong, Ting Wee (2022) Operational Modal Analysis of Singing Bowls. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Singing bowl therapy has become a popular treatment for sound healing nowadays. Many researchers claimed that the vibrations of sound from singing bowls aid in relaxing and have strong healing effects. A lot of studies have also been carried out to determine the fundamental frequencies of Tibetan singing bowls. However, there is a scarcity of data variations of the singing bowl resonance frequencies under actual performance conditions for Tibetan singing bowls and crystal singing bowls. Hence, in this research, an operational modal analysis will be performed to investigate the vibration and sound characteristics of singing bowls under actual performance conditions. A crystal singing bowl and a handmade singing bowl were selected as test specimens because this study is focusing on muscial B note. Since this study is focusing on operational modal analysis, a real mallet is used to measure the vibration and sound characteristics of singing bowls under actual performance. There are two techniques will be carried out to play the singing bowls which are striking and rimming. Modal parameters of singing bowls such as mode shapes, damping ratios and natural frequencies as well as sound spectrum graphs and acoustic response graphs are determined. The Finite Element Analysis of singing bowls is also conducted using ANSYS software. The results from Operational Modal Analysis (OMA) are validated and compared with numerical methods using Finite Element Analysis (FEA). The results obtained through OMA and FEA are in good correlation since the percentage difference is low and does not exceed 10 %. The fundamental frequency of the crystal singing bowl has been obtained which is about 493.20 Hz. The fundamental frequency of the handmade singing bowl also has been obtained which is around 123 Hz. The crystal singing bowl and the handmade singing bowl are calibrated to have musical notes of B4 and B2 respectively. Crystal singing bowl has a higher threshold sound pressure level compared to handmade singing bowl.