Abstract: Honeycomb structures, glass fiber mats, and polyurethane on both sides with respect to a perforated plate. A sound absorption hole is formed in at least one of the glass fiber mat and the polyurethane arranged on both sides of the honeycomb structure and passes through each cell, so that sound absorption performance in a high frequency band as well as a low frequency band can be improved using multilayer sound absorption characteristics. Noise passing through the honeycomb structure is changed to noise to be absorbed. Since the diameters of the sound absorption holes formed to pass through the honeycomb structures arranged on both sides of the perforated plate are different, a sound absorption band of a desired frequency may be easily adjusted. The sound absorption performance in a low frequency band of 1,000 Hz and a high frequency band of 5,000 Hz or higher can be improved.