Timbre maps to characterize the sound quality of the Japanese koto

Abstract

The Japanese koto and related zithers in East Asia are known for their distinctive sound quality (timbre), but the precise origins of the characteristics remain elusive. In an attempt to extend the knowledge of these characteristics, a finite element model of the Japanese koto(13 string plucked zither) was constructed using Comsol Multiphysics 5.1 based on a koto of known provenance and parameters. A series of experiments to identify the acoustical properties of the instrument were compared against results of the model. The results were then collated into a series of timbre maps to establish patterns of responses. This included overlaying eigenfrequencies, individual peaks from the spectra of the thirteen strings for the standard (hirajōshi) tuning, hidden peaks identified by the fourth derivative frequency scans and spectra from mechanical tapping of the reference instrument. The study shows that the anisotropy of the paulownia wood of the koto plays an important role in the vibration modes and frequency response spectrum. The timbre maps then identifies characteristics of the non harmonic responses that contribute to the koto’s distinctive sound and provide a template for the study of sound quality associated with culturally specific timbral preferences for East Asian zithers.