## 1 Introduction  
In response to the environmental impacts stemming from the linear produce-use-discard economic model, the construction industry is progressively transitioning toward a circular economic framework. This shift necessitates the closure of building material production loops, addressing the revision in using building materials like synthetic polymers and petroleum-based components, which are inherently non-biodegradable or necessitate extensive timeframes, often centuries, to decompose in landfills. Materials for acoustic insulation, specifically those made from synthetic mineral fibers such as glass wool, stone wool, and polystyrene, exemplify this [1]. There has been a growing interest in the utilization of biomaterials as a pathway toward developing more sustainable materials. Onesuch strategy is the development of composite biomaterials, composed of live organisms grown on biotic or abiotic substructures. Mycelium-based composites (MBCs) use fungal mycelium as a natural adhesive to turn waste into valuable resources [2]. A living network of filamentous threads, fungal mycelium, prospers when fed lignocellulosic waste [3]. Mycelial hyphae exhibit rapid growth within organic substrates, binding them into solid, lightweight foams with potential as alternatives to synthetic sound absorbers and insulators [4; 5; 6]. Previous research shows that mycelium-based composites are also good acoustic and thermal insulators [7; 8]. Mycelium's filamentous network creates a dense 3D structure with interconnected pores, providing inherent insulating properties [7; 9]. MBCs have been identified as an exceptional acoustic absorber of mid-low frequencies [10]. Several studies have explored the use of MBCs as acoustic absorbers [4; 8; 10]. These studies suggest that mycelium-based composites can present a biodegradable alternative to synthetic acoustic materials while still achieving optimal acoustic performance. At ForMat Lab, we have explored how the material composition, geometry, and surface shape affect the absorption properties of mycelium-based acoustic panels [8]. We have additionally explored how the configuration, quantity, and location of the panels affect room acoustics [11]. The mycelium strain, substrate type, and manufacturing methods, however, affect the insulation performance and scalability of mycelium-based sound absorbers [2; 10]. A significant drawback in current research on mycelium-based acoustic absorbers is the reliance on molds for fabrication, and current fabrication methods for mycelium-based composites are limited when it comes to achieving large-scale fabrication and geometric complexity. Recently, material extrusion-based additive manufacturing (EAM) that implements mechanical or pneumatic extrusion to deposit layers of mycelium paste has been proposed as an alternative to molding of MBCs [12; 13; 14; 15; 16; 17; 18; 19; 20], allowing for the manufacturing of unique shapes that can support the growth of mycelium, without the need for molds. In this paper, we present a research project on robotic EAM of living mycelium mixtures to fabricate biodegradable acoustic wall panels. This research is structured into four main steps: (1) formulation of extrudable mycelium paste, (2) parametric optimization of robotic EAM processes, (3) establishment of an experimental framework for acoustic property assessment, and (4) implementation of hybrid slicing methods for robotic EAM to fabricate acoustic wall panels. Previously, researchers have developed mycelium paste for mold-free composite fabrication [12; 13; 14; 16]. The formulation of an extrudable paste plays an essential part in attaining optimal printability of the mycelium-based composites. According to [PERSON] et al. [14], developing an extrudable paste with form stabilization qualities and optimal workability and buildability involves the incorporation of additives, such as fibers and binders, and the adjustment of water content and viscosity modifiers.