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Tritones & Why Locrian Mode “Doesn’t Exist”

Posted by Keith Freund On June - 27 - 20099 COMMENTS

theory-lesson2Note: This post requires a basic knowledge of intervals, which you can acquire by checking out my post Keith’s Crash Course On Intervals for Self-Taught Musicians. If you are not familiar with solfege syllables (do re mi fa sol), also read our Solfege Syllables To Intervals Translation chart.




This article comes as a response to a user question left in a comment on my article on modes. The question is:

Why (supposedly) can’t we hear Locrian mode?

Of all the seven modes derived from the major scale, Locrian is the only one considered to be a “theoretical mode”–one that our ears cannot actually hear. While there are supposed examples of Locrian mode, naysayers can argue that while these songs appear to be Locrian on paper, we hear them as a combination of chords borrowed from different parallel modes (“modal interchange”) or as being in a relative key.*

First, let’s explore what makes this particular tonality so interesting. Locrian is the only mode with a tritone interval and no perfect fifth (relative to the root note, not between the other notes of the key–in other words there is fi but no sol [see solfege chart]). This means that the root chord of a Locrian song is a diminished triad, which is comprised of the root, a minor third, and a tritone (the tritone would be called a diminished fifth in this context). It is this tritone that makes a diminished triad inherently unstable. While root chords are supposed to sound like a point of resolution or finality, tritones are so unstable that some say our ears can usually only hear them as going somewhere; we cannot hear a I diminished triad as ‘home.’

The most common place to find a tritone is in a V7 chord (V dominant 7), one of only a few seventh chords regularly used in classical music, and a chord which almost always resolves to I. The reason is because of its tritone. In my Intervals post, I explained that only intervals between the root and other notes are considered essential to a chord, not the relationships between the other notes. Tritones are the exception. This interval is so dissonant that it stands out in any context. The V7 has a tritone interval between its major 3rd and minor 7th. The major 3rd of a V7 chord will always be the leading tone (major 7th of the key or solfege syllable ti) and the minor 7th on the V7 chord will always be fa. When we listen to a V7 chord, our ears hear a strong pull from the leading tone up to solfege syllable do (root of the key) and from fa down to mi (major third of the key). Put do and mi together and you’ve got the I major chord.

Example: in the key of C major, a V7 chord is GBDF. B is both the major 3rd in this G7 chord and the leading tone of C major. F is the minor 7th and fa.

Technically speaking, there are several characteristics that are unique to a tritone. For one, it is the only interval which inverts to itself. For example, if you take the tritone interval from G to Db and flip it you get Db to G–another tritone. Secondly, it is the only interval which is not considered major, minor, or perfect. (It just is, man.) The tritone is in a league of its own.

Each of the 13 possible intervals are considered more stable (“consonant”) or less stable (“dissonant”). The tritone is one of the most dissonant. Played alone, a minor 2nd is more dissonant and jarring. This interval, like a tritone, is in neither the major (Ionian) nor minor (Aeolian) scales. In the context of a chord, however, a minor 2nd can sound quite pretty. In a major 7 chord, for example, the distance from the major 7th up to the root is a minor 2nd. But since we hear the major 7th interval going in the opposite direction, it sounds dissonant in a colorful way. Tritones always sound a little jarring to me (and yes, I’m including dominant chords). In the case of both intervals, our ear wants to hear perfect intervals (a unison and a perfect fifth, respectively), but they fall slightly short.

The latest pop song to come anywhere close to Locrian lately is Ciara’s “Like A Surgeon,” which features fi as the second bass note during the chorus (G in the key of C# minor). You could call this a borrowed chord (bVmaj7 from C# Lydian), but perhaps another brief flirtation with polytonality a la “Single Ladies” (both songs feature the writing and production of The-Dream and Christopher “Tricky” Stewart) because she sings minor 2nd (called a b9 tension in this context) over it, which is not considered an available tension on major 7 chords.

Most common examples of Locrian are riffs (short melodies which are repeated), not songs. The reasons why our ears tend to drift astray when hearing Locrian only apply to chords and harmony. Riffs are not like chords. They are more flexible. Because the notes are not occurring simultaneously (in the case of many rock riffs), our ear does not hear all of the same tendencies that intervals might suggest. All this being said, it’s hard not to hear YYZ as Locrian with the lead riff constantly reinforcing the root.

UPDATED: July 19th, 2011

I listen to all types of music, but I think you’ll see from this blog that pop music is what gets me excited. From years of working as an audio engineer, I’ve found that many pop songwriters (except the old school ones at the very top) have little, if any, formal music education. But the internet is changing all that, and I want to help in any way that I can. I’ve researched modes online to see what’s out there, and frankly most of it is either downright confusing or written exclusively for guitarists. So without further adieu…

Keith’s Crash Course on Modes For Self-Taught Musicians

You probably already know that there are two types of keys: major and minor (aka the “happy” and “sad” scales, respectively). But what if I told you that there are also 5 other exciting, sexy scales to choose from?

pianoPlay a major scale. Now play those same notes, but this time start from the sixth note (or “degree”) of the scale. You’ll notice that it sounds dark–you’re playing what’s known as the “relative minor” of your original major scale. Every major scale has one. Take C major and A minor, for example: they are comprised of the exact same notes (the white keys on the piano) but sound very different.

Already knew that? Here’s something you may not have tried: start from another degree of the major scale other than the first or sixth. These scales are called modes. You’ll notice that they have an unusual but not entirely unfamiliar sound. Each mode has its own general vibe. Technically, the major and minor scales are also considered modes, but songs written in these two most common scales are not thought of as “modal” music. Listed in order of degrees that they start from on the major scale:

1 – The Major Scale (aka “Ionian Mode”) – The most common scale there is.

2 – Dorian Mode – Minor with an exotic twist.* Often associated with the Eastern world, particularly Asia, or psychedelic music (see: the first half of “Come Alive“). Minor scale shape with a raised 6th degree (starting from the root of this Dorian scale, not from the relative major scale).

3 – Phrygian Mode – Darker than the regular minor scale. Most commonly used in metal and rap (see: “Swagger Like Us“). Minor scale shape with a lowered 2nd degree.

4 – Lydian Mode – Major with an exotic twist. Used mostly in film music and dreamy rock (see: intro to “Dancin Days“). Major scale shape with raised 4th degree.

5 – Mixolydian – Major with a rock edge. Defined the 90s pop rock sound (see: “Since U Been Gone“). Can sometimes sound Eastern. Often referred to as “Mixo” for short. Major scale shape with a flatted 7th degree.

6 – The Minor Scale – All styles. More specifically called “natural minor” or “aeolian mode.” I sometimes call it the “regular minor” scale because everyone knows what that means, but that’s not an academic name for it.

7 – Locrian Mode – A very unstable, confusing-sounding version of minor. (see: “YYZ“) Some argue that our ears cannot perceive a song as being Locrian for reasons which I will not get into. Minor scale shape with a flatted 2nd and 5th degree.

To make things even clearer, you can play the following scales with the notes CDEFGAB:

C Major, D Dorian, E Phrygian, F Lydian, G Mixolydian, A Minor, and B Locrian.

Now you’re probably wondering: “if all these scales use the same notes, how do we know what mode a song is in?” After all, if you read my compositional analysis of “Kids” by MGMT, you know that major key songs don’t always start on the root note.

Unfortunately that answer is mostly beyond the scope of this article and not always definitive. Each mode has its own identifying characteristics in a compositional context (versus a soloing context), but for now, try to hear which root note/chord feels like “home,” and use that information, along with which scale degrees are being used, to deduce what mode you’re in.

It can be tough to write something that actually sounds modal, because certain chords will cause the listener to hear the song in the relative major or minor key (the one that has the same notes as whatever mode you’re in). For this reason, there is typically very little bass movement in modal music.

Modes are not the end-all be-all of music or scales. Far from it. There are many other harmonic possibilities including pentatonic scales (5 notes per scale instead of 7), harmonic minor (regular minor with a raised 7th), songs where the key changes from section to section, songs that borrow chords from parallel keys, secondary dominant chords, and even songs with two different keys at once (polytonality). The list goes on. Nonetheless, being aware of modes will give you yet another tool for your songwriting toolbox.

I hope you’ve enjoyed this post. If there’s something you still don’t understand, feel free to leave a comment and I will do my best to clarify it. Theory won’t make you a great songwriter, and it’s certainly not required for becoming one, but you can think of it as a toolbox for understanding what you love or hate about certain songs and a potential cure for writer’s block.

*A great rock guitar player on getting through jazz solos: “play dorian over everything and people will think you’re hip.”


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