Hearing Backwards
Why does everything sound cool backwards? It doesn't matter what it is, play it backwards and you have a brand new unique sound. The big change you notice when playing a sound backwards is that the envelope of the sound has changed. The transients and attacks are gone. The sound sort of swoops into itself. It's a very exciting effect. Luckily, playing a sound backwards is also one of the easiest effects we can achieve with sound. Let's take a look.
In The Old Days
Back in the analog tape days playing a sound backwards was very simple. All you had to do was take the tape off of the machine, turn it over and hit play. Your recording now played backwards. It was slightly more complicated on multi-track tape machines because flipping the tape over changed the track on which the sound played back. In other words, a sound that was recorded on track 1 of a 4-track machine would play back on track 4 when the tape was flipped over.
The Digital Days
Nowadays, reversing a sound couldn't be easier. Almost every digital audio editor I can think of has a reverse feature. All you do is select the portion of audio you would like to play backwards and then select the reverse function. That's it!
Now Try This
If you have never tried applying time-based effects to a sound before you reverse it I would highly recommend you do so right now.
Select a sound to use for this example
Apply a heavy reverb with lots of decay to the effect. When I say apply what I mean is process the reverb onto the sound so that you have a new audio file to work with. Depending on your software this is often called "bouncing to disk" or "processing" the effect.
Take your new "reverb-heavy" sound and reverse it. What you should hear is a sound that builds slowly as the reverb tail flows directly into the actual reversed sound.
Try this same trick with a stereo multi-tap delay instead of reverb. I promise you'll love the results!
For more fun, try this variation of the above technique.
Select a sound to use for this example
Reverse the sound
Apply a reverb or delay to this reversed sound
Reverse your sound again. What you should hear is the reversed reverb or delay preceding or swooping into the original non-reversed sound. I use this effect all the time!
That should be enough for you to work with for now. Try these techniques out on your own sounds. As always, tell me what you think. Are these articles helpful? Have I left anything out? Leave me a comment and let me know.