3D-printed sound absorber considering ventilation

To reduce the noise in a ventilated system, three-dimensional (3D)-printed sound absorbers, based on multiple spiral waveguides, are proposed in this letter. A waveguide unit consists of a fixed-length cylindrical straight tube and a certain number of spiral tubes. The geometrical parameters of the spiral waveguides can be flexibly regulated, aided by the 3D digital modeling method to control the phase of the sound wave. Experimental results show that the proposed sound absorber can obtain the sound transmission loss (STL) about 9.6 dB in a frequency range of 300-1250 Hz with an 18% ventilation ratio.