Can polyester fiber acoustic panels solve the problem of low-frequency standing waves? How effective are they when used alone?

Single-layer polyester fiber acoustic panels excel at absorbing mid-to-high frequencies, but their absorption capacity for extremely low frequencies (<100Hz) is limited. To address low-frequency standing waves, a composite structure is recommended: add a cavity of at least 50mm between the acoustic panel and the frame, filled with high-density sound-absorbing cotton, or use it in conjunction with a thin-plate resonant sound-absorbing structure. For home theaters or recording studios, it is recommended to combine them with low-frequency traps for comprehensive treatment.