Bright and Dark Timbre Expressions with Sound Pressure and Tempo Variations by Violin-playing Robot

This study aims to build a violin-playing robot that can automatically determine how to perform based on the information included in musical scores. In this paper, we discuss the design of the variation pattern for the tempo of every bar and the sound pressure of every musical note to produce sounds that can convey bright and dark impressions. First, we present the analytical results of a trained violinist’s performance, in which we found that the tempo of the bright timbre is faster than that of the dark timbre, and the bright performance includes several steep variations in the sound pressure pattern. We then propose a design method for the performance to express bright and dark timbres based on the analytical results. In the experiments, sounds were produced by our anthropomorphic violin-playing robot, which can vary the sound pressure by varying a wrist joint angle. The sounds produced by the robot were analyzed, and we confirmed that the patterns of the produced sound pressure for the bright performance are similar to those of the designed one. The sounds were also evaluated by ten subjects, and we found that they distinguished the bright performances from the dark ones when the sound pressure and tempo variations were included.