Song Turtle allows you to select any point in an audio file and loop it for any duration. You can also change the playback speed of the file without changing the pitch. This is especially useful for musicians who want to learn a piece by ear: just load your file into Song Turtle, click and drag your mouse over the segment you're learning to loop it, and change the speed if you need to.
For more fine-grain control over loop sections, play the audio and press L right as the part you're learning starts. Song Turtle
will begin a loop there. When it's over, press L again and it will finish the loop and begin looping.