Slate Sound Structures for UMG Widgets in Blueprint

I am setting the style of my UMG widgets via Blueprint. Beside others this also allows me to set various sound effects, for example the click sound for an UMG button. The UMG “set style” BP nodes expect a “Slate Sound Structure” for their sound-based input parameters. However, I can’t find that type of structure when choosing the type of a variable.

How do I create/make a “Slate Sound Structure” variable?