Vibro‐acoustic measurement of several biwas

Abstract

The biwa is a family of Japanese lutes that have been played for more than 1000 years. This paper reports some measurements on the vibro‐acoustic characteristics of several biwas of different types. The main concern is the similarity and difference of the fukuju‐to‐table transfer mobilities among the individual biwas. Here, the fukuju is a kind of bridge whose shape and way of installation differ distictively from those common to the majority of other lute families found in many countries in the past as well as in the present time. The measurement revealed that in most cases the fukujus have two major vibration modes, to be labeled the ‘‘twist’’ and ‘‘flap’’ modes, with the corresponding resonance frequencies in the regions of about 0.9 to 1.2 kHz and of 1.4 to 1.6 kHz, respectively, though the exact figures depend on the physical size and shape. Their resonance property takes an important roll to determine the fukuju‐to‐table transfer mobility as the coupled vibroacoustic system with the table. The fukuju‐to‐table mobilities were compared with the spectra of the corresponding plucked sounds.