"Out of the Depths" (Psalm 130) shares several things with "How Long Will You Forget Me?" (Psalm 13).  Both were responses to a mentor's challenge of setting three Psalms to music, as Songs without Words. Both use the same melodic motif, and both explore feelings of abandoment and isolation. 

Out of the Depths is longer, more developed, and tracks the text of Psalm 130 more closely.