Low-broadband and thinning sound absorption structure design of embedded waveform tube coupled with coiled up space at high sound pressure

To address the issue that the performance of low-broadband sound absorption structures in high-sound-pressure noise environments is limited by thickness, a coupling structure of an embedded waveform tube and coiled space (EWTCS), along with a theoretical model, was proposed. First, based on the embedded rough tube model for low-amplitude incident sound waves and considering the nonlinear acoustic impedance caused by high-amplitude sound waves, an EWTCS model was developed. The accuracy of the model was then validated under both low- and high-sound-pressure incident sound waves. Furthermore, the particle swarm optimization algorithm was used for the structural optimization within the range of low-broadband sound absorption. The optimization results indicate that the structure achieved an average sound absorption performance of over 90% and a 17% reduction in thickness, reaching only 22 mm in the frequency range of 700–1100 Hz. In the broadband optimization process from 450–3000 Hz under incident sound pressure levels of 125–155 dB, the EWTCS achieved a 32.9% reduction in overall thickness, from 85 to 57.5 mm, while maintaining an average sound absorption performance above 83%. Finally, the accuracy of the proposed model and the effectiveness of the optimized structure were validated through acoustic testing using an impedance tube system. The optimized low-broadband sound absorption structure in this work offers the advantage of reduced thickness, showing potential for applications in aerospace and marine environments.