A resonant frequency analysis of the drum-sound rock in Mt. Palgong, Korea

초록

This paper examines resonant frequency of the rock which is famous for making a drum-like sound, from an acoustic analysis. The rock is made of granite with 3~4m thick. It is told that it makes the noise which sounds like a drum at first but in closer listening it sounds more like moktak, a wooden percussion instrument used by Buddhist monks for chanting. We found that the rock actually makes two different sounds, one similar to the sound of a drum and the other to that of moktak, depending on where and how to hit. In order to examine resonant frequency of the rock sound, we first formulated the equations for calculating resonant frequency for moktak. Then, we collected and analyzed the sound of the Drum-sound Rock and compared its sound to moktak. We also investigated the relationship between the sound and human auditory senses. Among some characteristics of the rock we found in our research, a drum sound has the fundamental frequency of 150Hz and lasts up to 500Hz, making relatively a flat and long lasting sound. A moktak sound also has the fundamental resonant frequency around 600Hz with undulation phenomenon of harmonics 3 and 5, making clear but repeated sound. The energy distribution of the sound is found in a narrow shape. In this paper, we also suggested where and how to hit the rock in order to make a specific sound between drum and moktak. © 2017 International Information Institute.

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