Impedance Tube Measurements of the Acoustic Properties of 3-D Printed Porous Materials.

The concept of acoustic impedance of porous media holds significant importance in acoustical engineering. One characteristic of a porous material that will influence its impedance is its airflow resistivity. This study examines the relationship between acoustic impedance and airflow resistivity through circular pores. By maintaining material and porosity as constants in 3-D printed porous material, the airflow resistance can be varied. The ability to design materials with specific porous properties offers a new tool for studying acoustic impedance. The porous media are designed using Python code to ensure the pores are uniformly spread across the porous media. This experiment uses a traditional impedance tube with a speaker at the top of the tube and two microphones above the porous medium at the bottom. Frequencies ranging from one 100 Hz to 1.5 kHz are measured. A separate device has been designed to independently measure the airflow resistance of the 3-D printed porous material. The measurements will allow us to compare airflow resistivity to acoustic impedance. This study can be used to influence the design of novel porous materials for acoustical use.