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The Music Theory Behind Vocal Tuners and Harmonizers

Apr 30, 2024

Up your vocal production game today by understanding the musical language behind vocal pitch and harmony effects.

The Music Theory Behind Vocal Tuners and Harmonizers

Vocal tuners and harmonizers are great tools for processing melodic vocal tracks and getting them to shine. They allow us to take an isolated, imperfect vocal take (or many) and polish it to musical perfection to work harmoniously in your mix. However, there’s a science to how these tools work, and if handled incorrectly, it’s hard to reap the true rewards they have to offer.

In this article, we’ll be taking a deep dive into the music theory behind vocal tuners and harmonizers and how to use them effectively, with Waves Tune, Waves Harmony, and Waves Tune Real-Time being our primary focus. In other words, if you’re looking to hone your melodic vocal processing skills, you’ve landed in the right place.

Basic Music Theory: Keys and Scales

Let’s get started by covering some of the basics to keep in mind when approaching singing and vocal tuning/harmonization.

First thing’s first, you need to be aware of what musical key your composition is in. Musical key is the most fundamental idea in music theory, with each key being based on a particular scale, or set of pitches. The key of your track dictates what musical notes will work together in any melodic sequence. If a note is played out of key, it will sound musically “off”.

Find the key of your song

The above image shows the keys of the Waves Tune Real-Time keyboard, with the notes for the scale of C Major highlighted. C Major is the easiest scale to memorize because it consists of only the white notes on a keyboard, meaning you can play any of the white notes in sequence and they’ll all sound in-key when working in C Major.

If you’re not familiar with how notes on a keyboard are structured, let’s take a second to explain. In the below image, you can see 12 notes labeled. These 12 notes make up a single octave and are the only 12 notes to make up the entirety of Western music theory. If you look closely, you’ll notice that the non-highlighted notes follow the same 12-note repeating pattern. That’s because they’re the same notes, just in higher or lower octaves.

Understanding the octave

Each octave starts with the note C. You can see from the previous image that the notes go up in sequence in this order: C, C#, D, D#, E, F, F#, G, G#, A, A#, B. Any typical Major or Minor scale (the two primary scale types that make up the majority of Western music) will consist of seven of those 12 notes. The musical key and prevailing notes are determined by the root note (the root note is the note the key is named after; e.g. the root note of F Major is F).

Recording an In-Key Vocal Using Waves Real-Time

Hopefully, you’ve taken some time to digest your breakfast of music theory basics and are now ready for some vocal tuning elevenses. Now, let’s take a look at how we can use our newly acquired knowledge of musical keys to record a vocal in-key using Waves Tune Real-Time.

As mentioned before, you first need to identify what key your composition is in. If you’ve written lyrics to an instrumental, the chances are the melody you’ve constructed will automatically follow the same scale as the instrumental. If your sung melody sounds out of key, you may need to rework it a little bit or rely on Waves Tune Real-Time to correct it (although you’ll achieve better results with an in-key base recording).

Find the key easily with Waves Key Detector

In the audio example above, the instrumental is in the key of F Minor. If you have an instrumental and you don’t know what key it’s in, you can use a tool like Key Detector to give you a good estimation. With Key Detector, you’ll get three keys that are most likely the key you need, from there you can try which one sounds in tune. Once you’ve identified the key to your song with Key Detector you can hit the Transmit Key button and the detected key and scale will be sent to the Waves vocal plugins in your session that are able to receive it. If you are unable to Transmit the key, you can make a mental note of the key and scale and enter it manually in your vocal tuning plugins.

Waves Tune Real-Time

Now, if you want to record live through Waves Tune Real-Time, you will need to record enable the audio track it is on. Within Waves Tune Real-Time, you can adjust the plugin’s settings to your preference very easily. If you’re pretty confident in your singing ability, you probably won’t need to go too heavy on the correction amount. However, if you’re intentionally going for that classic T-Pain or Travis Scott digitalized vocal then you’ll want to turn the Correction Amount to 100%, the Note Transition between 0.1-1.0ms, and the Speed between 0.1-10.0ms.

You can also adjust the range to suit your vocal type and play around with the Vibrato for some extra customization. If you possess a deep voice, you can opt for the Bass, Baritone, or Tenor pitch ranges; however, if you’re planning to hit those high notes, go for one of the remaining higher ranges.

Now, if you choose to record through the tuning correction from Waves Tune Real-Time the processing will be applied to your live vocal. The RAW unprocessed waveform won’t have the tuning effect baked in so you can always go back to make adjustments of the settings at a later time. Check out our example below over the instrumental from earlier, and while you’re at it, flick through this guide to natural vocal pitch correction to hone your tuning skills.

Tuning a Vocal Take Using Waves Tune

Okay, so we’ve covered recording live vocals with Waves Tune Real-Time applied, but what about if you have an old vocal recording that’s slightly out of tune and needs some correction? In this scenario, you have two options. You can either open an instance of Real-Time on your vocal’s FX chain or use the standard Waves Tune plugin to make manual corrections. As a note, you should insert any tuning plugin as the first plugin within a chain, with one expectation being when also using noise reduction plugins as well.

To use Waves Tune for manual pitch correction, open up an instance of the plugin in the first slot on your vocal’s mixing chain. Then, with the plugin open, allow the vocal to play, and the plugin will automatically import the audio with its pitch information. Your Waves Tune instance should then look something like the screenshot below.

Waves Tune pitch correction plugin

Now that your vocal is loaded into Waves Tune, there’s a lot of manual alterations you can make using the plugin. You’ll notice the vocal is spread across a keyboard note range. Waves Tune maps each distinct pitch change in the vocal to its corresponding note. You can use the music theory we spoke about earlier to manually move any out-of-key pitches onto a note that coincides with your track’s key. Read the final section of this article to know how to identify what individual notes are in your scale.

With Waves Tune, you can also interact with any of the plugin’s settings to make more advanced changes to each individual note. To find out more about these advanced settings, please refer to the Waves Tune User Manual.

But what do you do when your vocal has lots of out-of-key notes like our example vocal above? Well, Waves Tune is also capable of automatically correcting all of your notes to a specified scale at the same time. To do this, specify your desired root note in the bottom-left Segmentation panel, and change the Scale to Major or Minor (for our example we’re going with F Minor).

Get the pitch set perfectly in your vocals

You can then hit Select All, followed by Apply to map all of your notes to their correct key. Then, adjust the Note Transition and Speed settings and you’ll have a similar result as the one we achieved using Waves Tune Real Time earlier.

Adding Harmonic Layers Using Waves Harmony

Now we’re going to add some harmonic layers to our freshly tuned vocal. Go ahead and open up an instance of Waves Harmony on your vocal track. If you’ve still got the tuning applied from earlier, make sure to place your Waves Harmony instance after the tuning FX slot.

Waves Harmony

Waves Harmony allows you to place up to seven extra harmonic layers on your vocal at varying pitches across the stereo field. You can left-click anywhere on the visual stereo spectrum to add a new layer, or right-click on it again to remove it. You can also use your MIDI keyboard to add layers of your vocal according to the pitch of your chosen keyboard note.

We’re going to be using some more simple music theory to create some chords with our vocal. This can sound especially soothing to the ear if your chords stay true to some basic rules. Remember we said earlier that each musical scale consists of seven notes? A chord is made when notes sharing certain intervals are played simultaneously. For example, a triad chord is made up from the root note of the scale, the third note of the scale, and the fifth note.

Waves Harmony creating a chord

You can see from our screenshot and audio example that we’ve played F3, C3, and A#3 to create an F Minor triad chord of our vocal. If you’re struggling to figure out which pitches are the third and fifth in your musical scale, check out the final section of this article. Additionally, you’ll find all the help you need to get you harmonizing in this handy beginner’s guide to writing vocal harmonies.

Remember, triads are not the only chord type available to us. There’s a wide range of key combinations that can make up some pretty nice chords out of any musical scale. Some of these include introducing the seventh note, and even using inverted notes. We have a video below that dives a bit deeper into these advanced concepts if you want to explore chords further.

Extra Music Theory to Keep in Mind

Let us provide you with a quick formula so you can easily identify which notes to use when working in any given major or minor scale. Every major and minor scale follow the same pattern, so no matter what the root note is, the formula will be the same.

Every major scale follows the pattern of W, W, H, W, W, W, H, and every minor scale follows the pattern of W‑H‑W‑W‑H‑W‑W. Wait a minute, what do all those W’s and H’s mean? Well, a W indicates a whole note and a H indicates a half note. Each successive note on a keyboard (black or white) is a half note interval from their preceding note, so if you want to go up a whole note interval, you skip one note on the keyboard.

If we use the example of C Major again, you can test the W, W, H, W, W, W, H major formula to find that it holds true to no black notes being included in the scale. You can test these formulas on any starting (root) note and you will be able to identify each key’s seven notes.

If you’re still confused, don’t worry. Music theory is a whole language of its own, and it can take a bit of time to sink in. However, you should never feel intimidated by theory, whether it’s key signatures, scales, chords or otherwise. While being an extensive area of study, the core concepts are quite simple. For more information on essential music theory, check out this article on improving your productions.