Learn how to create vocal harmony parts and doubling effects using Flex Pitch and Logic’s vocoder plug–in.
Thanks to Flex Pitch, it is relatively easy to create great-sounding vocal harmony parts in Logic Pro X. First of all, we need a lead vocal to practise with. I have uploaded a suitable track to this month’s media page (https://sosm.ag/jan15media), along with some audio examples. Drag the lead vocal onto an audio track in Logic Pro X. Next, duplicate the lead vocal track and copy the lead vocal audio region onto the new track, so that you have two identical tracks containing the lead vocal. Now rename the new track ‘BVoc 1’.
We are going to go through the process of creating a backing vocal harmony part using the ‘BVoc 1’ track. In the menu bar above the main page, turn on Flex View by clicking the Flex View icon (see the red box in Screen 1). Next, in the ‘BVoc 1’ track header, click on the Flex pop–up menu and choose the Flex Pitch option (outlined blue in Screen 1). Double-click on the audio region in the ‘BVoc 1’ track to bring up the Audio Track Editor. (Make sure its pane is showing the Audio Track Editor and not the Audio File Editor — you can flip between the two by clicking the File and Track buttons at the top of the editing window.)
Go to the top of the Audio Track Editor and click the Flex View icon so that it is lit. We now have Flex View enabled in both the main page and the Audio Track Editor. In the Audio Track Editor, make sure you are displaying the Local Inspector, as this contains the Scale Quantize and Pitch Correction fields that we will use later. If you can’t see it, go to the View menu and click Show Local Inspector.
Let’s begin the process of creating a harmony part by selecting all the notes and dragging them down by three scale degrees. Hit Play to hear how the resulting vocal sounds when harmonised with the original; then try transposing it further.
At this stage it is unlikely that a simple transposition will sound good without further tweaking, unless you are moving things by a perfect fourth or fifth. What I tend to look for is a good starting point, or moments within a particular transposition that I find interesting. Once you have settled on a starting point, go to the Audio Track Editor’s Local Inspector and set the Scale Quantize field to the key signature of the track. If you are using the vocal example included with this article, set Scale Quantize to C sharp natural minor. Press Command+A to select all the notes, and then press the Scale Quantize Q button to snap all of the pitches to the key signature of the track. To further quantise the pitch, use the Pitch Correction slider: try setting it to 100 percent to hear what it is doing, then adjust it to taste. To alter the harmony part, keep the Scale Quantize set to the key signature of the track and adjust individual notes by click–dragging them up or down. Notice that as you move the notes up and down in the Audio Track Editor, Logic snaps the notes to your selected key.
Once you have finalised all the pitches of your harmony vocal line, you may find that the pitch-shifting artifacts make the vocal sound unnatural. To improve this we can adjust the formants of the vocal part. In the Audio Track Editor, press Command+A to select all the vocal notes, then go to the bottom right-hand corner of one of the notes and hover over the node. The mouse handle will display Formant Shift. I found that when creating two lower harmony parts, shifting the formants between –50 to –100 cents improved the subjective quality of the end result. An alternative place to make your formant adjustments is within the Track Inspector: go to the Extended Region Parameters box and use the Formant Shift field (see Screen 2). This is great for making quick overall adjustments to an entire region. Although Logic’s Flex Pitch sounds pretty good, I found I still wanted to apply a low-pass filter to the end result to remove high-frequency artifacts. Audio Examples 1 and 2 show the lead vocal with and without two-part faux backing vocals.
Once you have created your vocal harmony parts, you can then use Flex Pitch to create the illusion that they have been double-tracked. Duplicate the track and the audio file of one of your harmony parts and once again open the Audio Track Editor. First, let’s recreate the small differences in pitch you’d typically get between takes. Go through the vocal part and move the mouse point to the node above the middle of each note blob. The mouse handle will change to display Fine Pitch. Now, add small pitch offsets of between –20 to +20 cents to each note.
Next, we are going to recreate the small timing discrepancies that would be present in a normal backing-vocal recording. Move the mouse pointer to the front of each note, and the mouse handle will change to the resize icon. Now apply a small amount of adjustment, pushing or pulling the timing of the duplicate vocal part slightly away from the original. If you pan the original harmony track hard left and the new variation hard right, it gives the illusion of a double-tracked backing vocal and adds stereo width (see Audio Example 3).
A more unusual approach to vocal doubling is to use a vocoder to generate the double. This can be a great way to add more weight to a vocal, imparting a synthetic quality that might be desirable in certain dance genres, for example. Call up the lead vocal track in the Audio Track Editor and set the Flex Mode to Flex Pitch. In the local inspector, once again set the Scale Quantize field to the key of the track and set the Pitch Correction to 100 percent. This will help clean up the detected pitches of the vocal line before we export this as a MIDI file. Hit Play in Logic and make sure the lead vocal plays back with the correct melody, adjusting any of the notes that are incorrect.
From the Edit menu, choose Create MIDI Track from Flex Pitch Data (see Screen 3). This will create a software instrument track with a MIDI region containing the vocal line. Change the software instrument to Logic’s EVOC 20PS Vocoder, double–click on the vocoder to bring up its editing window and from the preset menu choose ‘Clear Voice’. From the side-chain input located at the top right of the plug-in instrument window, choose the audio track with your lead vocal on as the source. Hit Play to listen to the sound of the vocoder combined with the original lead vocal track. In my example, I needed to transpose the pitch of the vocal melody up an octave for it to be in the correct register to combine with the lead vocal track. Open the vocoder’s editing window and try tweaking the patch by adjusting the stereo width control to full and increasing the number of bands the vocoder has to 20 —this is done in the Bands field. Audio Example 4 contains just the vocoder sound; this could be layered in quietly behind a lead vocal in a dance track, to add weight and width. You can use the vocoder in this way to reinforce the lead vocal, or use the same method to add a synthetic quality to backing vocals. If you have multiple backing vocal parts, you can get really nice results by exporting their respective MIDI regions using the Create MIDI Track option from Flex Pitch Data, and then combining those regions into one region which can be used to drive the vocoder.
Logic Pro X has very powerful tools for experimenting with the pitch of monophonic audio such as a lead vocal — just be careful how much you show your singer, otherwise they may never record a harmony for you again!