The porous material with continuous pore is useful for the sound absorbing materia1 . In this research work , rice straw , rice husks , and buckwheathusks werc dealtas a por ( 川 s suund ubsorbing material that applied thc biomass . About rice straw , geometrical conditioll oi tha しwas reproduced in the narrow tube of the simple structure , and thc effect of absorbing sound ef the し ubule in the composite structure was vcrified . In the experiment , for the various thickness and thc back

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... were te$ted by using tl − ・ o 而 crophone irnpedance tube , and the nornlal incidence s 〔 川 nd nbsorption coe 鑷 cient was measurccl . Moreover , the absorp 亡i〔m coe 伍 cient was calculated from the aco 鳳 icaI constant obtained fr 〔 ) m the result of a mcasuremellt in a specific condition . And , these calculation vulues were compared wjth experiment values . As a result , i し was showmo be ab 正 e to estimate the absorption cocnicient of thc condition 〔〕 f the unmeusurernen し As fur rice straw . rice hvsks, and bu ¢ kwheat husks , it has been understood it has a usoful characterist1c 〔 】f abs 〔〕 rbing s 〔 } und . It leads to the fixa 仁 iol 】 of the carbon , and even if the incincration processing is dene , it is a carbon neutraL