In this video you are going to see how to add and split audio in Openshot.

First import clip in Openshot.
Drag & drop the clip on timeline.
Click on the play button to check it.

Import audio track.
Drag & drop the audio below the video track on timeline.
Click on the play button to check it.

Split Audio-
Drag the playhead where you want to split/cut the audio clip.
Click on razor tool and click on the audio clip on timeline. It will split the clip in two parts.
To deselect the razor tool again click on it.

Click on the audio part which you want to delete and hit delete key on keyboard.

Now play the video to check it

So this way we can split the audio in openshot