One of the first things I do when I sit down to create some new sounds is grab a few I want to work with and start pitch shifting them. For some reason sounds almost always take on a completely different and exciting vibe when you push them out of their normal pitch range. I would suggest that you try this on any of your newly recorded sounds. You are almost guaranteed to have loads of fun, as well as many new additions to your sound library. Here are the basics of pitch shifting sound.
Down Shift, Up Shift
Pitch-Shifting a sound down several octaves will often yield an eerie soundscape or drone. This works especially well with sounds that have sharp transients and a long decay, like cymbals and bells.
Pitch-Shifting a sound up a few octaves tends to give it a very sharp glassy sound. In some instances you will also begin to notice some rhythmic content in the sound that wasn’t obvious in the original. This happens a lot with speech. We talk in rhythmic patterns that aren’t really obvious until you speed things up by a couple of octaves.
The Mechanics of Pitch-Shifting
In the old days, the only way to change the pitch of a recording was to play the tape back at different speeds. Playing a tape back at half speed would cause the recording to sound an octave lower and double it’s original length. Analog tape machines, whether reel-to-reel or cassette, usually included some control that changed the tape playback speed. Most reel-to-reel machines allowed playback at speeds ranging from 7.5 inches per second (ips) to 30 ips. Cassette machines would often feature a pitch control knob that would alter the playback speed to certain degrees. The whole point is, record a sound at a fast tape speed and play it back at a slow tape speed. Instant Halloween sound effect!
Pitching-Shifting in the digital world is simple. Most digital audio software offer a pitch control that allows you to input how much up or down you would like to shift the original sound. One of the cool things about living in the digital world is that we are able to change pitch without changing the length of the sound, something that was impossible in the analog world.
One Thing Doesn’t Sound Like The Other
I would encourage you to try pitch-shifting your sounds in as many different ways as possible. If you have one, use a tape deck. Then turn around and pitch-shift that same sound in Pro Tools. You may notice a difference. Also, don’t assume that all digital audio software sounds the same. I’ve performed the same pitch shift effect on the same sound in Audacity and Digital Performer and they both sounded drastically different. Use this to your advantage when you are creating new sounds for your music.
What About You?
How many of you use pitch shifting on a regular basis? Is it something you never think about or is it a cornerstone of your sound design arsenal? Leave a comment and let me know. I’d love to hear from you.