This work investigates the use of topology optimization as a tool for the optimized design of acoustic barriers, aiming at reducing sound intensity in specific frequency bands. The Bi-directional Evolutionary Structural Optimization (BESO) method is used to distribute material in a fixed design domain, interactively adding or removing material to maximize the acoustic performance. The implementation uses a discrete distribution of the base material, without the use of intermediate materials, as in the case of the traditional SIMP parameterization. This approach avoids several problems related to the effective properties of an intermediate medium in the formulation of the topology optimization. Sound propagation is modeled as linear acoustic and the Finite Element Method (FEM) is used to evaluate pressure fields in different geometric configurations. The use of the topology optimization procedure ensures that the same mesh used throughout the optimization, ensuring consistency between finite element and sensitivity analyses at each iteration of the optimization process. The objective function of the optimization process is defined as the average of the sound pressure level in some target regions of the domain, evaluated from harmonic analyses at multiple frequencies. This approach ensures that the solution considers spectral variations associated with real situations, considering the sensitivity ranges of the human ear. The main constraint is the volume of material available for the construction of barriers, balancing acoustic efficiency, economic viability, and construction issues.Sensitivity analysis, essential for the effectiveness of the optimization process, is performed using the adjoint approach.The integration between BESO and FEM allows for the efficient exploration of non-intuitive configurations, speeding up the design process. The results demonstrate that the proposed methodology systematically reduces sound intensity in the defined frequency bands. The proposed approach paves the way for several practical applications of sound intensity control. All the computer implementation is avaliable at a free and open Github repository, bulit on the Open Source LSound program developed by the authors.
