A near-field vector sensing strategy for three-dimensional large-scale hybrid sound absorption

A near-field vector sensing (VS) strategy is developed for three-dimensional (3D) large-scale hybrid sound absorption based on a lightweight structure. By simultaneously detecting sound pressures and normal particle velocities at discrete positions on the absorbing surface, the reflected sound power is minimized to obtain the optimal secondary excitation. For the one-dimensional case, low-frequency quasi-perfect absorption could be realized by one-point VS. For the 3D case (at the incident angle of 20°), the optimized two-point VS is able to realize commendable broadband absorption from 50 to 800 Hz and extraordinary absorption between 50 and 300 Hz.