An evaluation study of mycelium based acoustic absorbers grown on agricultural by-product substrates

This research examines the use of a novel new renewable resource in acoustic absorption applications. The new material being tested is based on a fungi that is grown on semi-hydrophobic agricultural by-product substrates such as switch-grass, rice straw, sorghum stalks, flax shive, kenaf and hemp. The various substrates were tested as this novel composite is limited in the control over density, with the main control being the selection of the constituent parts. The testing of the material for use in acoustics utilized an impedance tube and measured the standing wave ratios in accordance to ISO standard 10534-1. The results of the study show the mycelium based boards are a promising bio-based composite alternative to standard traditional foam insulation board. Results suggest an optimal performance at the key automotive road noise frequency of 1000 Hz. A further advantage provided by this new material is that it can be produced economically in comparison to the traditional petroleum based foams with the further advantage of bio-degradation when the product is disposed of at its end-of-life use. Based upon this work, future research is planned to examine this novel new composite in other acoustic applications where shape modifications can further enhance the performance.