Some audio samples can be found in the Local 3D Library. You can drag and drop them like any other asset. By default they will play in a loop and be spatialised based on where you place them in your scene.
The Record section inside the Asset Library contains the list of recorded audio clips. To learn how to record a clip, click here.
We are currently working on creating a separate Sound Library and allowing you to change their settings. This feature is under development and will be available in a future release.