This research aimed to study the sound absorption properties of natural fibers and their reinforced composites.Sound absorption coefficients of three types of natural fibers,i.e.,ramie,flax and jute fibers and their composites were measured by the two-microphone transfer function technique in the impedance tube.The results were compared with synthetic fibers and their composites.It was found that both natural fibers and their composites had superior capability of noise reduction.The multi-scale and hollow lumen structures of natural fibers contributed to the high sound absorption performance.Moreover,the sound absorption properties of these natural fibers were also calculated by the Delany-Bazley and Garai-Pompoli models.They showed good agreement with the experimental data.It was concluded that multi-functional composite materials can be made by natural fibers so that both the mechanical and acoustical functions can be achieved. This research aims to study the sound absorption properties of natural fibers and their reinforced composites. Shrink absorption coefficients of three types of natural fibers, ie, ramie, flax and jute fibers and their composites were measured by the two-microphone transfer function technique in the impedance tube.The results were compared with synthetic fibers and their composites. It was found that both both natural fibers and their composites had superior capability of noise reduction. The multi-scale and hollow lumen structures of natural fibers contributed to the high sound absorption performance. The sound absorption properties of these natural fibers were also calculated by the Delany-Bazley and Garai-Pompoli models. The showed a good agreement with the experimental data. It was concluded that multi-functional composite materials can be made by natural fibers so that both the mechanical and acoustical functions can be achieved.