The sound quality of a classical guitar is greatly influenced by the Sounding Board. Strutting is attached to the back of the Sounding Board to maintain strength. At the same time, it is known that the strutting layout has a great influence on the sound quality of the guitar. Today, the layout of strutting tends to be fixed. Therefore, we made a guitar with a characteristic by reducing the number of strutting. However, the professional player's evaluation was "uninteresting sound quality“. Therefore, we applied a one-week light aging effect to the guitar by acoustic vibration. In this evaluation, the sound quality was evaluated by the combination of sound extension and timbre. In addition, the expression of the timbre can be calculated from many combinations of excitation positions and excitation methods. This guitar had better Sound extension than the conventional guitar even in the light aging state. In addition, this guitar can be evaluated as having a wide range of tones and excellent sound quality, and the same results as the hearing evaluation of professional players were obtained.
The purpose of this study is detection the call of Gallirallus okinawae from recording data for a long time. Gallirallus okinawae are Classified as Critically Endangered which natural monument and Endemic species of Okinawa. Gallirallus okinawae has been living in the forest without flying power, therefore, ongoing investigation of a long period of time is extremely difficult. Therefore, we have investigating of habitat throughout the year from recordings of Gallirallus okinawae sing in the fixed point. In this paper, we proposed a method of detecting a Gallirallus okinawae sing by performing the processing band-pass filter, the Hilbert transform, the envelope detection, the average rate of change calculated, the zero-crossing count for the digital sound data. I including the Hilbert transform into the original algorithm, the rate of accurate detection increased from 46% to 76%.