Sustainable acoustic absorbers from the biomass

There is currently considerable interest in developing sustainable absorbers, either from biomass materials or recycled materials, and it is the former that is the subject of this paper. A number of potential candidate materials are available from the biomass in the form of organic fibres. Non-fibrous materials, such as configurations of whole straw or reed, can also act as sound absorbers. A combination of impedance tube and reverberation chamber measurements have been carried out for a number of biomass materials and the effectiveness of current models for the prediction of the absorptive properties of natural fibres has been investigated. Examination of the acoustical characteristics of a range of natural fibres has confirmed their effectiveness as porous sound absorbers and also the limitations of current models for predicting their performance. Examination of the acoustical performance of materials consisting of different configurations of whole reeds and straws has revealed that these also possess considerable potential for application as broadband sound absorbers with particularly good low frequency absorption characteristics. The combination of natural fibres and whole reeds offer the possibility of developing a range of sustainable absorbers which act very effectively across the complete audio frequency range.