In addition to youriPod library you can add songs from other audio and file sharing apps like DropBox, GoogleDriver, or 4Track. You start by first opening the the app containing the source audio file. Next you export it to Slow Down Music Player. The tricky part if figuring out how to select the file and export it. Here is an example of how to add files from DropBox. The steps are basically the same for all other apps.
In our example we assumes you have already opened DropBox and that we want to add the audio file 'Francine'. Depending on the source app the process for selecting and exporting will be a little different
After you tab on 'open in' you can scroll to the left and right to find apps that can work with your selected file.
It takes a little while for IOS to launch Slow Down and copy the file over.