University of Tsukuba
Tuning of membranophones is important to design timbre, while it is difficult for inexperienced players, due to the insufficient ability for judgment of pitch difference. In this paper, we propose tuning scheme for membranophones, substituting visual information for auditory information. First, vibration modes shape of the head membrane are visualized, based on the measurement of sound pressure on the head membrane by a circular microphone array, and we estimate the tension distribution of the head membrane, especially unbalance in tightness of the pair of rods on oppositional position, make the nodal line of the (1,1) vibration mode change. Second, we propose a tuning scheme for membranophones based on information on the state of the nodal lines of the mode shapes, visualized based on the microphone measurements, and the difference of eigenfrequencies between the orthogonal modes. We show that the proposed scheme is helpful to make the head tension uniform, as the results of experiments using the vibration of tom-tom with only one side head stretched as an example of actual membranophones. We expect this scheme to train the tuning ability for inexperienced players.
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