In our digital age, pitch shifting has become a simple process that allows us to manipulate the pitch of an audio waveform higher or lower. This allows for countless applications, a notable example is how Matt Stone and Trey Parker create the voices for their animated show South Park – they record the audio in their ‘broken’ man-voices and then with some studio wizardry, they pitch them up to sound like children.
Pitch shifting used to be achieved solely through transposition where the audio’s pitch was changed by speeding up or slowing down the entire waveform. This would be fine for changing the pitch of small samples of audio, but when performing drastic changes the audio quality is reduced, never mind the samples new length. Now, through miracles of audio alchemy, pitches can be altered without changes to the sample length and vice versa – however this is not completely perfect as audio quality is still being lost when drastic changes are performed in the waveform.
When used in the music environment, pitch shifting is most famous for being the core mechanic in how auto-tuning works. Once a key for the song is established, auto-tuning is a plug-in on a track that reacts to the frequencies it processes and then pitches then up or down in accordance with the key. Simply put it puts out of tune audio back in tune. In this context pitch shifting is a powerful tool that can work in real time, even in live situations – sorry to ruin the ‘magic’ of the X factor. I’ll move away from Auto-tuning for now as it is an entire blog topic in itself and is abundant in popular music with artists like T-Pain using it as an effect rather than just a ‘make-me-sing-good’ button. Hell, even Obama is at it.
True Tape Flanging
I came across this technique when making my way from the front cover to the last of Bobby Owsinski’s “The Mixing Engineer’s Handbook” – an essential addition to any aspiring audio engineers library. Flanging is a common plug-in in most digital audio software but before digital, how was it created?
“Flanging, another name for an artificially induced comb filter, got its name from the fact that the effect is achieved by actually slowing down a reel of tape by holding your finger on the edge of the reel flange (the metal piece on each side of the tape that holds the reel together).” – Bobby Owsinski
Now with digital there are no tapes so it becomes an on-screen process rather than a trying to squish your fingers in the CD drive or jamming a fountain pen in your USB port. The effect can be achieved in a few simple steps and can be varied depending on how much ‘flanging’ you want in your mix:
I. Duplicate the audio you want to flange (I have sampled an acoustic guitar).
II. Highlight the duplicated region and go to AudioSuite > Pitch Shift and set the shift down in cents (if using semitone scale) by anything up to 10 (this is by no means a law, just a guide).
III. Nudge back the duplicated region by 1 or 2 ms – Nudge settings can be found below and regions can be nudged by using the + and – keys on the numeric keypad (Pro Tools 10).
First example with flange (pitched down one cent and nudges back one ms):
Second example with a little more flange (pitched down 3 cents and nudged back two ms):
One more thing…
If you are having trouble with out of tune vocals try duplicating the original audio and pitching one of them up one cent and the other down by a cent and blend them with the original. This should ‘trick’ the ear by taking away the focus of any sketchy notes.
I hope you got some use out of this and please feel free to ask any questions : )