From the main menu bar, select .
A Create Section dialog box appears.
Enter a section name. For more information on naming objects, see Using basic dialog box components.
Select Other as the section Category and Acoustic interface as the section Type, and click Continue.
The section editor appears.
Select an acoustic medium material for the acoustic interface section. If desired, click to create a material; see Creating or editing a material, for more information.
Enter a value for the section Plane stress/strain thickness. If the section will be used with a two-dimensional region, you must specify the section thickness. Abaqus/CAE ignores the thickness information if it is not needed for the region type.
Click OK to save your changes and to close the section editor.