ブナ二次林の音場環境の解析

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Summary : In this study, we paid attention to sound effect inside of forest stand. The sound inside the forests was caught as the environment resources. A change in the sound environment caused by the change in the forest environment was caught from the viewpoint of stage. The part shape district of 20 m×20 m was installed in the Fagus Crenata secondary forest inside the Kaminagawa experimental forest, Yamagata University. The trees inside of investigation district were divided at random by 3 and were cut into three times. Recording investigation was done four times; before felling, after 33% felling, after 67% felling, after the clear cutting. One notebook personal computer was used as the sound wave sending machine. 8 musical scales were outputted in every 1 octave from 110 Hz. One more notebook personal computer was used as the digital recorder. It was recorded in the PCM mode of 44 kHz three times. Volume and Basal area decreased at the fixed rate. In the case of the frequency character, differences were seen in 880, 1760, 3520 Hz and 440, 7040, 14080 Hz. It was found that the former 3 sound is easy to reflect toward the latter 3 sound. And, it was thought that tree number, Volume and Basal area influence the reflection and the absorption of the sound inside the forests. In case of the resound characters, the amount of decline of the sound pressure level after one second was compared. As that result, the amount of decline was on the increase by all the sending sound of 440-14080 Hz at the time of the felling rates 33% → 67%. In case of 880,1760, 3520 Hz, it was the tendency that the increase and decrease of the amount of decline was the same. And, it was found that there was very long resound time in this investigation applicable area.　　Key Words : Fagus Crenata Secondary Forest, Sound seen, Digital recording, Frequency properties, before and after thinning　　キーワード：ブナ二次林，音響環境，デジタル録音，周波数特性，間伐前後
山形大学の論文
2008-02-15

ブナ二次林の音場環境の解析

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