Mushrooms’ root-like mycelium transformed into sustainable acoustic treatments

Timothy Hsu, assistant professor of music technology at the Herron School of Art + Design, plays the piano inside a sound booth featuring a sustainable acoustic panel made from mycelium, the root-like structure found in fungi. Photo by Liz Kaye, Indiana University

Timothy Hsu, assistant professor in music technology at the Herron School of Art and Design at Indiana University Indianapolis, is a "fun guy" when it comes to research. By harnessing the power of mycelium, the branch-like structure that comprises the root network of mushrooms, Hsu is making some noise in the field of acoustics.

He and his colleague Jonathan Dessi-Olive, an assistant professor of architecture at the University of North Carolina at Charlotte, are fabricating sustainable sound panels and structures made from a composite of mycelium and other organic materials and testing them for sound-absorption, transmission and reflection. Their research could also create options for soundproofing - a clear differentiator from what exists in the acoustics and architecture market today.

Acoustic treatments can be found almost everywhere, including restaurants, schools, office buildings, homes and recording studios. As a graduate student at the Georgia Institute of Technology, where he earned a Ph.D. in mechanical engineering (acoustics), Hsu focused his research on the acoustics of hospitals.

Without sound paneling, a room with flat, hard walls will create an echo, which can be distracting in the wrong environment. Acoustic design creates quieter, calmer spaces, making communication and concentration easier.

"One of the most common types of panels is this foam, fuzzy stuff you see on the walls," Hsu said. "Sound waves go into it, and because it's fuzzy inside, the energy will be lost in there to heat and friction. The result is that sounds don't get reflected back as strongly."

Researching mycelium-based acoustic treatments

Acoustic paneling is traditionally fabricated using petro-chemical foam or fiberglass, a material made from a combination of glass and resin. Hsu said that while some companies tout the sustainability of fiberglass, the material is not easily recyclable and can be harmful to the environment.

Hsu and Dessi-Olive's ultimate vision is to see less sustainable materials replaced with mycelium, a biodegradable building material that can literally be grown and reproduced naturally. According to Hsu, mycelium has gained popularity in recent years as a sustainable replacement for carbon materials.

"At IKEA, they use this type of material as packaging replacements," Hsu said. "There are also some high-end fashion designers using parts of mycelium as a leather replacement."

The cultivation process for the researchers' mycelium acoustic materials is done at UNC-Charlotte, where they grow the mycelium, providing wood chips or hemp as a substrate for the root-like system to latch onto and grow around. They also add a small amount of sugar or flour to feed the growth process. They place the pre-grown material into wooden or 3D-printed molds, so it grows into a specified shape. At the end, they bake it.

Once the mycelium is ready, Dessi-Olive ships discs of the material to IU Indianapolis, where Hsu performs small-scale testing for transmission and absorption using a large cylinder apparatus called an acoustic impedance tube.

Clay Seders, a senior studying music and arts technology at Herron, assisted Hsu with the mycelium research during the past year. He was able to do so through the Undergraduate Research Opportunity Program, which provides funding support for students to work with a mentor on real-world problems. The program gives students opportunities to gain research and scholarly skills that relate to their coursework and future careers.

Clay Seders, left, a senior studying music technology in the Herron School of Art + Design, and Timothy Hsu, assistant professor of music technology, place mycelium-based acoustic discs inside the acoustic impedance tube, which will record absorption and transmission levels. Photo by Liz Kaye, Indiana University

"Assisting with this research has been immensely fascinating and gratifying," Seders said. "It has made me much more effective in working through these ideas that are fundamental for acoustic analysis."

Seders said he aims to work in an acoustic treatment and design firm to design spaces and analyze room acoustics. He is also interested in working within the materials industry, designing new kinds of acoustic treatments, which is why the opportunity to work with Hsu on this research is invaluable to him.

"Being able to assist in writing a legitimate research paper has been massively educational," Seders said. "It has helped me improve the way I interpret data, ask important questions to expand the scope of ideas surrounding the research, and convey the data, ideas and interpretations in a much more effective way."

Hsu said they have made significant progress but still have more work to be done. He said one of the challenges is finding ways to make the mycelium materials more bendable. The original designs they created are flat sheets, and Dessi-Olive was able to create bended sheets and shape them into sweeping structures that were hung from the ceiling as part of an installation at UNC-Charlotte. Since mycelium is somewhat fragile, they are working on incorporating other materials to give it skeletal support, similar to how rebar is used in reinforced concrete.

Companies that are selling mycelium-based acoustic products don't always address common issues such as transmission loss, Hsu said.

"We are looking at expanding our research into adding more structural integrity, incorporating other sustainable materials to modify the acoustic and structural performance of the panels and creating larger scale sculptural 'art' installations that will potentially have customizable acoustic responses," Hsu said.

The next steps in their research include finding funding and space within a gallery on campus or in Indianapolis to exhibit one of their mycelium acoustic design structures and showcase its acoustic properties. Hsu said they hope to create something that would include a live music performance interacting with the structure.

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