Today, we’re going to be taking a look at some basic music theory, covering some of the main theoretical principles and concepts that form the foundation of theory. Like any other language, music has its own alphabet. Here, we’re taking a look at that music alphabet, and how it relates to playing a musical instrument. This is by no means the only system in existence, and in fact it’s only really been around as we know it today since the mid-19th century. This musical system consists of twelve notes of equal temperament, meaning that the distance in pitch between one note and the other is the same.
This guide will be focusing on theory that’s applicable directly to playing an instrument, so we won’t be going into reading or writing music here. Rather we’ll be looking at the principles you’ll be using when learning an instrument (such as guitar or piano), and certain terms that you’re going to come across that are very useful to know, since they provide the foundation for future learning.
Table Of Contents
The Music Alphabet
The twelve notes used in most modern music consist of seven alphabetical letters (A-G), also called the natural notes, and five ‘sharps’ or ‘flats’. The mathematical roots of the relationships between these tones is found in ancient Chinese and Pythagorean principles, and although extremely interesting, are beyond the scope of this discussion. We’re only looking at the basic theory of music for now. These twelve tones or notes, when used in different combinations, form the building blocks of pretty much all the songs you hear when you switch on the radio today.
If you look at a piano, the natural notes are the white keys, while the sharps and flats are the black keys. The diagram below illustrates how all twelve notes are set in relationship to each other :
The black keys (sharps and flats) fall in between certain letters. A note is sharp if it is defined by the natural note before it, or flat if it is defined by the natural note coming after it. For example… there is a note that comes after F, and before G. This is called F sharp (denoted as F#) or G flat (denoted as Gb). So F# and Gb are the same note, just different ways of referring to the same pitch.
But not all alphabetical letters have sharp or flat notes between them. If you look at the diagram above, you’ll notice that there are a couple of spaces in between natural notes with no sharps or flats. Similarly, on a piano, you’ll notice that some white keys do not have black keys between them. This occurs between B and C, and also between E and F. All other natural keys have sharps/flats in between them.
Semitones and Tones
Now let’s look into certain terms used to define the relationships between these different notes, using the image below as reference :
The interval between any one of these twelve tones to the next one in the sequence is called a semitone, while a gap of two semitones is called a tone. For example, in the iamge above, going from A#/Bb to B is a semitone interval. Going from E to F is also a semitone interval, since even though they are both natural notes, there is no sharp/flat key in between them.
A tone is an interval of two semitones between two notes. Therefore going from B to C# is a tone interval, since this interval covers a distance of two semitones (from B->C then from C->C#). Going from F# to G# is also a tone interval, since in between these two notes there is a G (from F#->G then from G->G#).
What’s an octave?
The twelve notes keep cycling around once you get to the end of all twelve of them. Essentially, an octave is an interval of twelve semitones. Therefore, if you start at C for example and go up by an interval of 12 semitone steps, you will arrive at C again. If you had to play these notes on an instrument, the note name would be the same, but the pitch of the second C would be twice as high (twice the frequency) of the first C in that octave.
In other words, an octave is therefore the distance between two notes of the same name but with an interval of 12 semitones in between them. The higher of these two notes will have a pitch that’s twice as high as the low note in that same octave relationship. Referring to the image above will help you to visualise this.
Notes on a Piano
On a piano, a semitone is the distance between a white key and a black key (or another white key if no black key exists in between). The following diagram shows the different notes on a piano. You might be able to see the relationship between the diagram below and the first diagram above, detailing all twelve tones.
Also note how the notes simply start cycling again once all twelve tones are used. Therefore the second C you see below is twice the pitch of the first C, since one is an octave above the other :
Notes on a Guitar
The numbers below the diagram indicate the fret number on the guitar. The word open before a letter means that the string is played without pressing down on the fretboard.
On a guitar or a bass, a semitone change is achieved by going up by one fret on the same string. Therefore a tone interval is played by going up by two frets. For example, if 3rd fret of the open E string is a G (light purple), then the 4th fret on that same string would be a G#/Ab (green), while the 2nd fret would be an F#/Gb (dark purple).
Going from the G to G#/Ab is a semitone (red), while going from G to A is a tone (orange). This applies also when playing chords… for example, moving an F Major chord up in its entirety by one fret means that it now becomes an F# Major.
An important note about octaves on guitar. Guitar notes are a bit more complicated than piano, since not you can have the same note, with the same pitch, played on different parts of the guitar. Therefore not all the notes you see with the same name in teh image above are octaves of each other. Some of them are quite lieterally the same note just played in a different position. I won’t get into the details here, since this article is about the basics of music theory rather than about guitar.
These principles of basic music theory that we’ve looked at should be more than enough to get you started with learning an instrument and understanding the underlying principles behind what notes are which and why they’re organised in a certain way. Like any other subject, music theory can get as vast as complex as you’d like it to get, but hopefully this information has helped you enough to get you motivated to keep learning about this wonderful system we call the language of music.