Hybrid labyrinthine-based metamaterials for low-frequency noise attenuation

This work introduces a new method for mitigating unwanted sound in manufacturing environments that require solutions with minimal size and mass. The approach utilizes specially engineered acoustic metamaterials, which are both cellular and graded, to achieve superior performance. Compared to a standard hollow cylinder, these developed structures improve sound-blocking capabilities by approximately 40 decibels. Their resonance behavior is also enhanced, with the initial resonant response starting at a frequency 400 Hz lower. Furthermore, the materials display an exceptional capacity for absorbing sound, with measured coefficients of 0.7 and 0.8 in the difficult low-frequency spectrum of 200 Hz to 250 Hz. Weighing about 30 grams and measuring only one centimeter thick, this technology provides a powerful and practical technique. It is highly effective for insulating against low-pitched sounds, particularly in applications where both weight and space are primary concerns.