Creating Micro-Resonator in Metallic Structure by Laser Powder Bed Fusion for Enhancing Acoustic Absorption

Noise-induced hearing loss often results in a characteristic notch within the 3–6 kHz frequency range, which is crucial for speech intelligibility. However, traditionally fabricated metallic sound-absorbing structures designed for harsh environments frequently suffer from issues such as large structural dimensions, low manufacturing precision, and inadequate programmability and repeatability. In this study, we developed a microscale resonator-similar structure incorporating a Helmholtz resonator, which was fabricated utilizing laser powder bed fusion technique for applications in harsh environments. These structures not only demonstrate a pronounced sound absorption peak around 3022 Hz, achieving a coefficient of 0.92, but also maintain an impressive average sound absorption coefficient of 0.69 within the critical 3–6 kHz range. Compression tests indicate that the specific energy absorption of these resonator-similar structures reaches 45.8 J/g, demonstrating a significant advantage in energy absorption capabilities, providing dual protection against mechanical stress and noise. This research seeks to explore the application of metal AM technologies in the field of sound absorption, contributing to the development of lightweight and effective metallic sound-absorbing structural components suitable for industry, vehicles, and military fields.