Pitch Correction Effect

You can use the Pitch Correction effect to correct the pitch of incoming audio signals. Improper intonation is a common problem with vocal tracks, for example. The sonic artifacts that can be introduced by the process are minimal and can barely be heard, as long as your corrections are moderate.

Pitch correction works by accelerating and slowing down the audio playback speed, ensuring that the input signal (sung vocal) always matches the correct note pitch. If you try to correct larger intervals, you can create special effects. Natural articulations of the performance, such as breath noises, are preserved. Any scale can be defined as a pitch reference (technically speaking, this is known as a pitch quantization grid), with improperly intonated notes corrected in accordance with this scale.

Note: Polyphonic recordings, such as choirs, and highly percussive signals with prominent noisy portions can’t be corrected to a specific pitch. Despite this, feel free to try the plug-in on drum signals!

Pitch Correction Parameters

The Pitch Correction effect offers the following parameters.

Figure. Pitch Correction window.
  • Use Global Tuning button: Enable to use the project’s Tuning settings for the pitch correction process. If disabled, you can use the Ref. Pitch field to freely set the desired reference tuning. See Setting the Pitch Correction Reference Tuning.
  • Normal and Low buttons: These determine the pitch range that is scanned (for notes that need correction). See Defining the Pitch Correction Effect’s Quantization Grid.
  • Ref. Pitch field: Sets the desired reference tuning, in cents (relative to the root). See Setting the Pitch Correction Reference Tuning.
  • Root pop-up menu and field: Click to choose the root note of the scale from the Root pop-up menu. See Defining the Pitch Correction Effect’s Quantization Grid.
  • Scale pop-up menu and field: Click to choose different pitch quantization grids from the Scale pop-up menu. See Defining the Pitch Correction Effect’s Quantization Grid.
  • Keyboard: Click a key to exclude the corresponding note from pitch quantization grids. This effectively removes this key from the scale, resulting in note corrections that are forced to the nearest available pitch (key). See Excluding Notes from Pitch Correction.
  • Byp(ass) buttons: Click to exclude the corresponding note from pitch correction. In other words, all notes that match this pitch will not be corrected. This applies to both user and built-in scale quantization grids. See Excluding Notes from Pitch Correction.
  • Bypass All button: Provides a quick way to compare the corrected and original signals, or for automation changes.
  • Show Input and Show Output buttons: Click to display the pitch of the input or output signal, respectively, on the notes of the keyboard.
  • Correction Amount display: Indicates the amount of pitch change. The red marker indicates the average correction amount over a longer time period. You can use the display when discussing (and optimizing) the vocal intonation with a singer during a recording session.
  • Response slider and field: Determines how quickly the voice reaches the corrected destination pitch. Singers use portamenti and other gliding techniques. If you choose a Response value that’s too high, seamless portamenti turn into semitone-stepped glissandi, but the intonation will be perfect. If the Response value is too low, the pitch of the output signal won’t change quickly enough. The optimum setting for this parameter depends on the singing style, tempo, vibrato, and accuracy of the original performance.
  • Detune slider and field: Detunes the output signal by the set value.
  • Input Detune slider and field (Extended Parameters area): Detunes the input signal by the set value, thus affecting it before any pitch correction takes place. This parameter is of particular benefit when automated.

Defining the Pitch Correction Effect’s Quantization Grid

Use the Pitch Correction effect’s Normal and Low buttons to determine the pitch range that you want to scan for notes that need correction. Normal is the default range and works for most audio material. Low should be used only for audio material that contains extremely low frequencies (below 100 Hz), which may result in inaccurate pitch detection. These parameters have no effect on the sound; they are simply optimized tracking options for the chosen target pitch range.

The Scale pop-up menu allows you to choose different pitch quantization grids. The scale that is set manually (with the keyboard graphic in the plug-in window) is called the User Scale. The default setting is the chromatic scale. If you’re unsure of the intervals used in any given scale, choose it in the Scale menu and look at the keyboard graphic. You can alter any note in the chosen scale by clicking the keyboard keys. Any such adjustments overwrite the existing user scale settings.

There is only one user scale per project. You can, however, create multiple user scales and save them as Pitch Correction plug-in settings files.

Tip: The drone scale uses a fifth as a quantization grid, and the single scale defines a single note. Neither of these scales is meant to result in realistic singing voices, so if you’re after interesting effects, you should give them both a try.

Open the Root pop-up menu to choose the root note of the scale. (If you chose user scale or chromatic in the Scale pop-up menu, the Root pop-up menu is non-functional.) You may freely transpose the major and minor scales, and scales named after chords.

Excluding Notes from Pitch Correction

You can use the Pitch Correction effect’s onscreen keyboard to exclude notes from the pitch quantization grid. When you first open the effect, all notes of the chromatic scale are selected. This means that every incoming note will be altered to fit the next semitone step of the chromatic scale. If the intonation of the singer is poor, this might lead to notes being incorrectly identified and corrected to an unwanted pitch. For example, the singer may have intended to sing an E, but the note is actually closer to a D#. If you don’t want the D# in the song, the D# key can be disabled on the keyboard. Because the original pitch was sung closer to an E than a D, it will be corrected to an E.

Note: The settings are valid for all octave ranges. Individual settings for different octaves aren’t provided.

Use of the small bypass buttons (byp) above the green (black) and below the blue (white) keys excludes notes from correction. This is useful for blue notes. Blue notes are notes that slide between pitches, making the major and minor status of the keys difficult to identify. As you may know, one of the major differences between C minor and C major is the Eb (E flat) and Bb (B flat), instead of the E and B. Blues singers glide between these notes, creating an uncertainty or tension between the scales. Use of the bypass buttons allows you to exclude particular keys from changes, leaving them as they were.

If you enable the Bypass All button, the input signal is passed through unprocessed and uncorrected. This is useful for spot corrections to pitch through use of automation. Bypass All is optimized for seamless bypass enabling or disabling in all situations.

Tip: You’ll often find that it’s best to correct only the notes with the most harmonic gravity. For example, choose “sus4” from the Scale pop-up menu, and set the Root note to match the project key. This will limit correction to the root note, the fourth, and the fifth of the key scale. Activate the bypass buttons for all other notes and only the most important and sensitive notes will be corrected, while all other singing remains untouched.

Setting the Pitch Correction Reference Tuning

In Logic Express, the settings that appear when you choose File > Project Settings > Tuning determine the tuning reference for all software instruments. In MainStage, choose MainStage > Preferences > Tuning (in the General tab).

If you turn on the Use Global Tuning button in the Pitch Correction window, the host application Tuning settings will be used for the pitch correction process. If this parameter is turned off, you can use the Ref. Pitch field to freely set the desired reference tuning (to the root key/note).

For example, the intonation of a vocal line is often slightly sharp or flat throughout an entire song. Use the Reference Pitch parameter to address this issue at the input of the pitch detection process. Set the Reference Pitch to reflect the constant pitch deviation in cent values. This allows the pitch correction to perform more accurately.

Note: Tunings that differ from software instrument tuning can be interesting when you want to individually correct the notes of singers in a choir. If all voices were individually and perfectly corrected to the same pitch, the choir effect would be partially lost. You can prevent this by (de)tuning the pitch corrections individually.

Automating the Pitch Correction Effect

The Pitch Correction effect can be fully automated. This means that you can automate the Scale and Root parameters to follow harmonies in the project. Depending on the accuracy of the original intonation, setting the appropriate key (Scale parameter) may suffice. Less precise intonations may need more significant changes to the Scale and Root parameters.