View Full Version : Music Theory

12-12-2011, 03:48 AM
Here is a post that someone posted on another site that I found to be very helpful. I have included his contact info at the end of the post in order to give him credit. I hope this helps some others as well.

Oh, yea, FWIW, T and S stand for Tone and Semitone in American music theory.

"All autoharpers should have a grasp of this, and it does keep cropping up all the time, so here is my take, for the archives, as simple as I can make it, please feel free to skip.

Notes are sounds. There are an infinite number of sounds.
One way of defining a sound is by how many cycles of energy there are in a second, measured in Herz. The note we call A, for example, usually is 440 Hz (beats per second). But what about the note at 441Hz - what do we call that? Or 440.1Hz?
So we have to select some notes that we all agree on. One guide to help us in our selection is that notes that are double the beats or half the beats, sound similar. We say that these notes are an octave apart, and give them the same names. So the note at 220 Hz will sound like a lower A, and 880Hz will be a higher A.

So we now have octaves. How do we divide these up? In Western music, we have chosen to split each octave into twelve notes, using simple ratios, like thirds, quarters and fifths of the gap between the two notes at the octave. If we start at C, these notes are named C C# D D# E F F# G G# A A# B .. and then back to the C of the next octave up. Why?
BECAUSE!!! Note there is no E# and no B#. Why? That's just the way it is!! And if we count backwards, A# turns into Bb (B flat) and so on. If you look at the piano, these are the notes you will find - the black notes are the sharps and flats, and there is no black note in-between B and C, or E and F. Each of these notes are said to be a semitone(ST) apart, and two semitones make a tone(T).

Turns out that to Western ears, you often do not need all of those notes to play a tune that sounds good, so we often write music that just uses 7 of them. To help us select which 7, we use a pattern. No matter what note you start on, you pick the next note according to these gaps : T,T, ST, T, T, T, ST and you have something we call a Major scale. In C that would be: C D E F G A B and back to C - look at the twelve note scale and convince yourself that the gaps between those notes are correct - C-D is a tone, D-E is a tone, E - F is a semitone, and so on. This subset of notes is called the SCALE of C major and tunes using this scale are said to be in the KEY of Cmajor. We set up other Major keys by using the same pattern - G major is G A B C D E F# G - the F# comes in because a tone up from E is F#, and the gap of a semitone added to that brings us back to G. Each of these scales is what we sing when we sing do ray me fa so la te do!

If we use a different interval pattern, we can set up different subsets of notes, that we give us different keys or modes. I won't go into those.

OK. So that's how we choose our notes, and that's how we define which notes belong to which keys. Now what happens when we play those notes together?

Two notes together are called an interval. This is fairly straightforward at first, but gets more complex! A C and an F played together is a fourth - the notes are 1 and 4 in the C major scale. C and G are a fifth apart. There are lots more complicated names for more unusual intervals, that I won't go into here.

Three notes or more played together give you a chord. Chords that sound good are made from notes that are 1, 3 and 5 in the list of notes in that key, starting at the lowest note.
So a C major chord has the notes C E and G - 1, 3 and 5 starting at C (C (D) E (F) G). A G major chord has the notes G B and D - 1, 3 and 5 starting at G, using notes from the scale of C major only. What other chords could you have in C Major, just using the 8 notes that you have available? Well, F major is F A C, that is easy. But what about Aminor, A C E? Why is it called a minor chord?

Look at the intervals that make up that chord. In a normal major scale, we use T T ST T T T ST, remember? Use this pattern and count up from the A - A B C# D E F# G# A - you see what happens? we get three sharps appearing! Which is why the key signature for A major is three sharps. So an Amajor chord would have to be A C# E. But there isn't a C# note in the scale of Cmajor, so we invent a new chord based on A, A C E which we call Aminor. Similar arguments apply to Eminor - E G B, and Dm - D F A. They each use notes from the scale of C major, but result in chords that we cannot call major chords because the gaps are wrong.

Now the numbers. The chord built up from the first note of the scale - any major scale - is called the I chord. It is a major chord. The chord built on the second note is called the ii chord - we use little Roman numerals because this is a minor chord. In the key of C major, the ii chord is Dminor. Similarly the iii chord - Em in the key of C major.
The IV chord and V chord are both major chord - F and G in Cmajor. The vi chord is minor - Aminor. The seventh chord is a peculiar one! It does not fit the pattern for a major chord or a minor chord, and is called a diminished chord - we hardly ever talk about that one.

Other chord patterns exist. To make a seventh chord, for instance, like G7, we take the G major chord - G B D - and add the seventh note of the scale of Gmajor -FLATTENED! So the seventh note of the scale of Gmajor is F# - flatten that and you get F - flatten means take it down a semitone, sharpen means take it up a semitone! Other sevenths are available, but this is what we generally mean when we see G7.

So the chords that you see for O Holy Night are all made from the 7 notes that make up the scale of Cmajor - the song is in the key of Cmajor. The advantage of writing them out in number form is that this lets you play it in any key very easily. In Cmajor the I, IV and V chords are C F and Gmajors. In Amajor, these would be A, D and Emajor - still the I, IV and V chords.

The numbering on the sheet music is as you suspect. In autoharp playing we use what we call Rhythm chords and Melody chords. Rhythm chords are what you would play if you were just singing along to the song. Melody chords are the chords you need to be holding down if you want to play the melody on the autoharp.

Hope this helps. It really is worth understanding the logic - or sometimes lack of logic, just common practice - behind the chords and the notes. Apologies for the long post, but this is still just scratching the surface of musical theory - though it is certainly enough to be going on with."

Bob Ebdon

12-12-2011, 09:03 AM
This is fantastic. Thanks for sharing it.

12-12-2011, 09:47 AM
Thanks a lot to both you and the original poster.

I'm sure this will help me a lot in my pursuit of deeper understanding of music and the ukulele!


12-12-2011, 10:05 AM
Cool! I think I just jumped into the water without learning to swim first, so to speak but I've always wanted to learn the theory so I can apply it.

12-12-2011, 12:24 PM
Just one small thing: I'm amazed at how logical it all is. The more I delve, the more logical it is. The entirety of music theory is on your side. It's there to makes sense of things. And at it's deepest level, it's actually very elegant.

Take, for instance, the circle of 5ths. The circle of 5ths is a series of notes, based on the simplest ratio of frequences with give you two different frequencies. It's the first harmonic which is a different note. Basically, it's the simplest difference in the world of sound.

So, you start with C. Add 5ths. G D A E. Rearrange those, and you have C D E G A, the C pentatonic scale.

Add a few more, C G D A E B F#. Rearrange them, and you have G A B C D E F#, a G major scale. Even major scales are made up of 5ths.

When you change key, it usually sounds smoothest if you go up or down: that's right, a 5th.

One relationship, the 5th, and it defines so many things.

12-12-2011, 12:57 PM
One relationship, the 5th, and it defines so many things.

Heinrich Schenker much?

12-12-2011, 01:02 PM
Thanks for posting that. It's really useful.

Just one small thing: I'm amazed at how logical it all is. The more I delve, the more logical it is.

There are studies that indicate a similarity in the way brains process music and the way brains understand mathematics. Some researchers have suggested that the elimination of music-related classes in public schools may actually make it more difficult for children to learn mathematics. (Research like this has also led expecting parents to play music from composers like Bach and Beethoven to their unborn children.)

12-12-2011, 01:17 PM
My old HS band director used to say that the older you get, the harder it is to learn theory. It's not because we get too old to process things, it's because we adult types like for things to be logical, to make sense. Music theory mostly does just that.. BUT to get to the point where it all starts to make sense, you have to get through a lot of: Why?? Because I said so! First. Like there's a reason, but you won't understand until you learn more. We like for things to make sense from the start.

Not impossible of course, it's just an obstacle that some find easier to deal with than others. I don't know if that helps anyone, but it helped me deal with why chorus I couldn't learn some basic things without it being a huge production.

modern day ukuleleist
12-12-2011, 05:23 PM
I'm trying to learn music theory for the first time at age 21.

And yeah, there are a lot of times when I can't help but ask why. For example, why would you use double flats or double sharps? (As in, why bother calling a D note Ebb or Cx?) I'm trying to get through this stuff, but I feel like it won't stick in my brain until I understand the reasoning behind it.

12-12-2011, 11:26 PM
For example, why would you use double flats or double sharps? (As in, why bother calling a D note Ebb or Cx?) I'm trying to get through this stuff, but I feel like it won't stick in my brain until I understand the reasoning behind it.
All of that is because the notes don't live their own individual lives, they're (almost) always referred to as part of the key you're playing in. So an Ebb is a flat Eb, and not a D, either because the key (and the scale) you're playing in has an Eb, or maybe even an E that you're massaging a bit more than normal. So a note isn't named after its frequency, it's named after the key its in and its purpose in that key.

For the same reason you can find several different names for some same-fingered chords: What you call it depends on the key you're playing in.


Ukulele JJ
12-13-2011, 02:08 AM
Luckily, double-sharps and double-flats are pretty much the absolute last thing you need to learn in the world of music theory. :-)