Pitch Shifting Tips and Tricks with ReaPitch

Pitch shifting is a valuable tool for working with all aspects of recorded music. It can be used to tune a note to a certain key or even change the key of a song. By applying it, you can provide a whole new dimension to a sample, keeping the familiar sound but changing it enough to fit in your song. I'm going to talk about all the ways you can implement it, from very basic, to fairly advanced. The plugin I will use to demo it is REAPER's ReaPitch, freely available as a stock plugin for REAPER or downloadable as part of their free FX suite. [EDIT: apologies for misinformation, this plugin is not included in their FX suite, I am in looking for a free plugin of quality to link here and will post one hopefully soon]

While not pretty, ReaPitch is incredibly powerful 
and a brilliant tool for pitch shifting.

So the very first thing you are going to want to try if you haven't used pitch shifting already, is the most basic of shifts. ReaPitch allows you to pitch up and down in cents (green), semitones (red), and octaves (blue).

With simple music theory, you will know that cents are 1/100 of a semitone, and there are 12 semitones in an octave. Use this to your advantage when pitch shifting so you can use the correct resolution of adjustment. 

If you want to change the key, use the semitones fader, if you want it to stay in key but play much more high/low pitched, use the octave fader. If you want to make a minor adjustment, e.g. the sample or sound is a bit flat/sharp, you are best using the cents fader.

To get the sample in key with your song, it helps to know what key the song is as well as the key of the sample. Then you can simply adjust the sample up or down to match the song. If you don't know the key of the sample, there is key detection software that will help you find it out. 

Note that these are not always accurate so always use your ears (or someone else's) to judge.

If you listen to a lot of dance music, you may recognise the pitch shifted sound of vocals. As heard below in Warrior's Dance, by The Prodigy, the vocals sound sped up. This is because the voice resonates at frequencies according to the size of the vocal tract. 

By pitch shifting up, you note only increase the pitch of the notes sang, but the pitch of the resonances created by the mouth and throat. This is why some songs sound "chipmunked". If you consider how a male and female voice can sing the same note, but the female voice still sound distinctly higher, it is the resonances themselves which are higher pitched.

So, this brings us onto the formant settings. These leave the notes sang or played untouched while moving the resonances up and down.

If you play around with the formant, you are essentially modifying the size of the singer's vocal tract. You can turn a female voice into a male voice and vice versa.

To avoid the chipmunk effect, you can counterbalance the pitch shift with a negative formant shift. Let's have an example:

There is a vocal sample which you are pitching up 6 semitones. This will be enough to shift the resonances up and make the chipmunk sound. It will also mean the sound of the vocalist will change as their vocal tract will sound smaller.

To maintain the sound of their voice, turn the formant down 6 semitones to bring the resonances back to where they should be. It will suddenly sound like the singer again, with the difference being their voice is singing at a much higher pitch.

Use the formant to "restore" the vocal identity of 
the singer

You can also make chords with ReaPitch. This is done by the Dry/Wet faders on the left. We shall use a "power chord" sound made famous by rock guitarists. 

Pitch the vocals up by a 5th (seven semitones) and move the dry fader all the way up. You will now hear both the original sound, merged with it's perfect fifth above it. 

Feel free to adjust the formant to make it sound like it was double tracked by the same singer in harmony, or leave it as it is. If you change the formant to a setting other than -7 semitones, it can sound like a different singer in complete timing and harmony as the main singer.

Mix the wet setting to taste (I like keeping the Dry/root note at 0.0dB and the wet at a few decibels below).

Same thing can be done with adding an octave above or below. This can create some awesome sounds as heard in a lot of modern electronic music where there is a vocalist singing and their voice is also heard (at lower volume) an octave down. This can really fill out the space if it is needed although sounds heavily effected.

ReaPitch has an awesome feature of tabs, where you can add as many different pitch shifts as you like. This has an awesome "monk chanting" effect provided you know what intervals to stick to so it doesn't stray from the key signature.

Each tab can have a full pitch shift dedicated to it, with the volume independently controlled by the volume fader above the Add Shifter button. To get a monk-chant-like effect try pitching down by an octave, up by a perfect fifth, and add a perfect fifth over the lowered octave. Try with other intervals too but that is a good way to get started. 

Do not try and use this live or if latency is an issue. Each tab of pitch shifting does add a considerable delay and so is best done as post recording processing. Unless it is a very slow song, the vocalist or instrumentalist will hear the delay and be put off.

Finally, all the controls can be automated. This is very useful if you want to add some variation to a sample, perhaps a drum sample (more info here) or maybe by automating the formant up to create a rising effect without altering the key. This is great for builds before a drop (more info here).