You can add sound effects (SFX) in APlay to your slides to be played via Apple TV or Web Player.

1. Go to APlay Playlists
2. Go to the Media Tab
3. Select "My Uploads"
4. Create or Select an existing Library
5. Drag your .wav or .mp3 file into the library
6. Wait for the file to complete the upload
7. Click the 3 dots on the right of your new file
8. Select "Edit"
9. Drag a thumbnail onto the "Custom Thumbnail" box
10. Select Finish
11. Now you can add this media to any playlist and add the playlist to the queue.