## 1 Introduction
According to a study by [PERSON], [PERSON], and [PERSON] [25], using WHA in place of some of the cement decreases corrosion and weakens the concrete's resistance to chloride erosion. Sugarcane bagasse is a waste product that comes out of the sugar manufacturing industries. It is a fibrous waste that is obtained after sugarcane juice has been squeezed out of the sugarcane. If not well managed, it can cause environmental pollution and thus, finding ways of recycling it can help to solve the environmental pollution caused by such agricultural waste [26; 27; 28; 29; 30]. However, these wastes have an advantage over other waste materials in that they are renewable. Sugarcane bagasse contains about 50% cellulose,  
Figure 1: Modern earth blocks used in the construction of walls of houses (images taken from houses under construction in Busia Country, Kenya). 25% hemicellulose, and 25% lignin [31]. When burnt, the sugarcane bagasse forms ash (sugarcane bagasse ash, SBA), which contains traces of metals such as silver, arsenic, barium, chromium, gold, and lead [32]. The chemical composition of WHA has been investigated, where its main components have been found to include silica (64.88%), alumina (6.40%), calcium oxide (10.69%), and iron III oxide (2.63%), with a specific gravity of 2.20. Of these, silica, alumina, and iron III oxide, which should contribute at least 70%, are the contributors to the pozzolanic reactions [33]. The acoustical characterisation of compressed earth blocks has been explored, including the works by [PERSON] et al. [34] and [PERSON] et al. [35], who investigated the effect of compaction pressure on porosity, airflow resistivity, tortuosity, and viscous characteristic length. The studies found out that addition of both compaction pressure and cement led to a decrease in the porosity and a corresponding increase in the airflow resistivity of the CEBs. However, these two studies considered only cement as the binder to the soil. In a recent study by [PERSON] et al. [36], the acoustics (acoustic transmission coefficient, porosity, and airflow resistivity) of WHA and lime were explored. This study therefore did not consider SBA as a binder to the earth. A study by [PERSON], [PERSON], and [PERSON] [37] also explored the sound intensity that was transmitted through walls constructed using CEBs in comparison to wood-framed walls. The study found out that the CEB walls were better than the wood-framed walls in that they reduced the noise by half and, therefore, provided more isolation between the interior and exterior acoustic sources. In this work, the influence of varying the binder type (WHA and SBA) and their concentrations on acoustical properties (acoustic transmission coefficient, porosity, and airflow resistivity) were studied. The porosity and airflow resistivity were determined using the equivalent fluid model (EFM) by solving an inverse acoustic problem [38]. This study's specific objectives were (i) to determine the impact of WHA content on the acoustical properties (acoustic transmission coefficient, porosity, and airflow resistivity) of compressed earth blocks (CEBs) and (ii) to determine the impact of SBA content on the acoustical properties (acoustic transmission coefficient, porosity, and airflow resistivity) of CEBs.