TUNE IT UP
In addition to traditional audio processing effects such as equalizers, compressors, reverbs, etc… there are a number of digital effects that alter sound in a more self-evident, apparent way. Love it or hate it, pitch correction (auto-tune) is one of these effects.
You are probably aware that recording vocals can be a very time consuming process. In the past, music producers would spend countless hours re-recording vocalists until they captured an ideal intonation. Today, due to the emergence of pitch correction, this process has been expedited.
Generally speaking, pitch correction is most commonly used on vocals to smooth-out intonation problems from note-to-note. However, like all insert effects, it can be fed any input source on the fly.
HOW DOES PITCH CORRECTION WORK?
Pitch correction does not audibly affect speed, level, or contour. Specifically. the unit detects the actual pitch of a digital signal (using a “live pitch” detection algorithm), calculates the necessary change, and modifies the audio signal accordingly.
Today, there is a multitude of pitch correction plugins and insert effect units available. However, regardless of the instance you use, the pitch correction process is virtually the same (with the exception of parameter ranges, modulation features, and/or the processing algorithm itself).
In today’s lesson, I will demonstrate the “auto-tune” effect using a freeware VST called MAutoPitch made by Melda Production. Furthermore, I’ll walk you through the fundamental features of this unit and provide tips on how to reach desirable effects.
The top- left portion of MAutoPitch contains the following parameters :
Depth determines the amount of pitch correction that is applied to the signal as a percentage.When you set this knob to 100%, you are affecting the entire signal. At this setting, the output should sound “machine-like” – perfectly in tune. At lower “depth” settings, it processes just a fraction of the signal. This leaves more deviation – more mistakes.
Speed defines how quickly the plugin reacts to the incoming signal from note-to-note. The higher the speed, the more immediate the pitch correction is.
Detune defines global pitch change in cents (100 cents = 1 semitone = 1 half-step). This parameter gives you control over how accurate the correction is.
The top-right portion contains these parameters :
Dry/Wet determines the ratio of original to processed signal. 100% wet means you hear only the processed signal, 100% dry (0% wet) means you only hear the original signal.
Width determines the pitch processing differences between the left and right stereo channels. You can use it to achieve a stereo expansion effect.
Keep Formants :
Keep Formants preserves the spectral characteristics and timbre (natural sound) of the input. Turning this parameter down is a cool effect but can result in inconsistent timbre/articulation, which may make some lyrics unintelligible.
Formant Shift :
Formant Shift lets you manually alter formant information. This, generally, does not transpose the fundamental pitch. Rather, it changes the apparent size of the sound source.
Bottom section contains scale panel and tuning indicator.
Scale panel :
The Scale Panel allows you to select the scale to which the input will be tuned to. The note buttons (C, C#, D, D#, E, F, F#, G, G#, A, A#, B) allow you to choose the tonal center of the scale. You may select chromatic, major, minor, or pentatonic formulas. “Chromatic” means the pitch will be corrected to the nearest half-step. “Major” will tune the signal to the nearest scale degree diatonic to major. “Minor” does the same as “major”, but to the nearest scale degree diatonic to minor. “Pentatonic” tunes the signal to the nearest note in the pentatonic scale. You may also punch-in your own custom scales using the piano roll. This way, the signal is tuned to the nearest notes you enable.
Tuning indicator :
The Tuning indicator displays the frequency correlation between input and output. In most cases, the green bar (output) will be shorter than the red bar (input) because the length indicates how “in – tune” each signal is. The note name to the left of the indicator bars shows the enabled pitch nearest to the pitch of the input.
PRACTICAL USE & AUDIO EXAMPLES
In the first place, the idea of pitch correction is to conform a performance to the key of your song (see blog: Scales, Intervals). Below is a short song of mine in which I processed the vocal using pitch correction. I chose this particular vocal phrase because it features a lot of vibrato. Since vibrato affects pitch periodically, it nicely exemplifies the corrections made by “auto-tuning”.
The first example is a clean vocal with poor intonation, which is a typical problem. In addition, a properly tuned bass accompanies the vocal sample.
In this second audio example I accordingly applied a plug-in called MAutoPitch to the same vocal. Basically, I set the plug-in to the key that the bass is in (G Phrygian). Also notice that the vocal and the bass are now in harmony.
Lastly, I applied a bit of simple reverb to the vocal to emulate a bigger performance space.
In final consideration, let’ us hear how it suits our song.