The thickness of the micro-perforated plate (MPP) used in sound absorption usually does not exceed 1.5mm due to the difficulty of punching. A dense honeycomb core is presented to replace the micro-perforated plate to improve the sound absorbing performance in low frequency. The perforation ratio of the honeycomb is controlled by punching large holes in a thin face plate which is fixed to the honeycomb core. This structure is named low frequency honeycomb sound absorber (LFHSA) in this article. The sound absorbing performance of LFHSA is measured in an impedance tube. The LFHSA and back space in a limited 100mm depth show a good sound absorbing performance in frequency range 100-300Hz.
