Reasons To Reverse A Track

So you are in the middle of a song and losing momentum. Perhaps you have a couple of guitar riffs and that synth is sounding good but you cannot think of another way to express it. You are on your third run through of possible samples and truly stuck to find one that suits. Time is running out - the longer you are stuck, the more likely you will give up on your gangsta-jazz album's opening song. You may indeed feel like this:

Any minute now, the song just wont be worth the frustration and you 
and all your sheep backing vocalists will become dog meat.

I have a solution. Reversing a track, in particular a small segment of a track is the best way of finding a new idea. In fact the idea may be so perfect, you don't even want to re-record it. You may indeed be happy with it the way it is. 

Another reason to reverse a track is your playing skill. I like playing guitar, in particular metal and rock. Shredding is not a strong point but I like doing it. By reversing a small phrase of technical guitar, you may find a riff that your skill may not allow you to perform. 

If you are editing a track to remove bad language or drug references, you may not want the gaps in vocals or even worse a cut out of the backing track too. Gaps in vocals kill the flow and ruin the song. Here is an example of a censored Eminem song that sounds bad because of the offending words have been silenced.

Instead of cutting the words out, you could just select the words and reverse them. Most DJ software allow this, known as the "censor" function. By reversing the swear word (think "gnikcuf"), it is not apparent  what is said while the sound of the voice and melody remain. If you only have the master track, it will affect the instrumentation and sound odd, but will be immensely better than just cutting out the music all together. 

Finally if you want to insert satanic messages that prompt angsty teenagers to kill themselves in their masses, do what the Beatles did and just play reverse recordings of people speaking over your track this is called backmasking.