In this study, the pore structure of carboxymethyl chitosan aerogel (CCSA) was modulated by adjusting the concentration of carboxymethyl chitosan (CCS) in combination with targeted freezing. The hierarchically porous structures were obtained by the freeze-drying process. The results show that the CCSAs prepared by directional freezing have excellent broadband acoustic absorption properties, and also expand the scope of application of CCSAs in practical applications due to the excellent thermal and mechanical properties of the prepared CCSAs. Since the CCSAs prepared by directional freezing still has excellent antimicrobial properties, it also provides a new strategy for aerogels with acoustic properties to be used in medical industry applications.