Resonance and directivity effects of an engineered tweeter grille on frequency response

We investigate the potential effects of Helmholtz resonance and sound directivity using a modified tweeter grille featuring a defined array of pores. Unlike conventional acoustically transparent grilles or fabric covers, this grille is intentionally designed to alter the tweeter's on-axis and off-axis frequency responses while providing physical protection. The concept can also be extended to the high-frequency range of midrange drivers. In a previous study, Helmholtz resonance effects were found to be limited, likely due to the tweeter's low acoustic output and the influence of non-plane wave modes, such as break-up frequencies commonly seen in tweeter diaphragms. To enhance effectiveness, a compression driver may be used as the sound source. The grille could also serve as a platform for evaluating and optimizing waveguide performance in compression drivers. To assess the grille's acoustic impact, we employ COMSOL Multiphysics simulations and Klippel measurements, along with DeltaEC—a thermoacoustic modeling tool developed by Los Alamos National Laboratory—to analyze resonance behavior and its influence on the frequency response.