Mycelium composites are a novel material type. Mycelium is the ‘root’-network of a fungus and can be used to grow shapes on substrates of agricultural waste fibres. A few designs exist that use the material and information on material properties is limited. The goal of this thesis is to find out how mycelium composites can be produced, designed with and perform in an acoustic building product. A literature study on material properties shows acoustic absorption and thermal insulation are suitable functions for this material. The thesis describes impedance tube tests done on samples of mycelium and existing acoustic building products, reverberation room tests done on larger panels and shows microscopic images of the surface and sections. By growing the panels myself, a lot of hands on experience is gained, which was used to gather input for designing acoustic building products. Balancing acoustic absorption with mechanical properties and connecting the panels to the wall are important issues that have to be addressed, while there are opportunities in creating shapes and in sustainability. The designed panel was compared with existing mycelium, other bio-based and more conventional products in terms of acoustics, safety, health, durability, sustainability and price.