Intervals and chords

This lesson focuses on the music theory of these concepts.  While much of this is not really necessary in order to play from sheet music, there are terms that you need to understand in order to be in the mainstream of music.  Sooner or later you're going to need to know the language to interact with other other musicians and music instructors (paid or otherwise).  The goal is to explain at least the basics and to help decode the terminology.  This is by no means complete but it gets you started.


In a nutshell, an interval is the distance between two notes on the 12 note scale, measured as a count.  For example, how many intervals are there from C to E?   To easily compute, just look at a keyboard, start with any C note key and count up on both white and black keys until you get to E.  Don't count C itself.  So we say the interval from C to E is 4.  Still starting with C, you could do this for every note in the 12 note scale and you would have an interval range from 1 (from C to C#) through 12 (from C to shining C in the next higher octave).  You could also repeat this for all the other scales with roots D through B.  Each would have the same interval range 1 to 12.  If only the music world would use this count to identify intervals, it would be pretty simple.

So while the interval is a simple concept, it gets complicated by the terminology.  For every interval, there is a historically based name commonly used by all musicians.  In an earlier lesson, it was explained that the original music scale had 7 notes but over time was expanded to 12.  So in the former, the interval range was just 1 to 7, while in the latter (today) it's 1 to 12.  It was also explained that no revamping of music terminology was made as a result of the expansion.   So what we have is shown in the table at right.  

The table lists the intervals by count and by name with an example based on starting with the note C as an example.  The starting note in the interval is called sometimes the root, and sometimes the tonic.  It has an interval count of zero, the distance to itself (see the bottom line of the table).   Thus, the interval count distance to the note E is 4 and that count is named a Major 3rd.

To help you visualize this, the figure at left shows the original 7 notes on the white keys on a scale starting with C (which is the way most musicians visualize a scale these days).  The numbers on the bottom of the keys are the interval count from the root C.  Thus, the root of this scale is C, the 1st note,  and the 7th note is B.  The term major almost indicates the original 7 notes except that even that is not consistent.  Here's why.  If you play both the root and 5th note at the same time you are playing what is called a chord.  The chords that correspond to intervals of 5 and 7 sound so pleasing to the ear that the term perfect has been substituted for major.  Logically, they could also be called a Major 4th and a Major 5th, but typically they're not.

Four of the 5 "new" notes are indicated with the term minor.  In the C root scale, these are represented by the black keys.  The exception to this naming convention is that one in the middle, with an interval of 6, which is called either an augmented 4th or a diminished 5thAugmented means one interval higher while diminished means one interval lower.  Again, logically speaking, it could be called a minor 5th.  But it's not.   

So here's the bottom line.  Remember that an interval can be between any two notes and on any scale.  And that this is one of many examples where you simply have to memorize these terms and what they mean in terms of intervals.  You need to do this if you ever want to interact in any way with the mainstream music world where these terms are ubiquitous.  For now, the important ones to focus on are the major and perfect intervals.  Fortunately, you don't need to know the names to play them.


Chords are really important because they bring so much more "depth" to the sound of a piece of music.  

They are simply the playing of two or more notes at the same time, and generally with the same hand.  So while there can be up to 5 notes played in a chord, in this course you will see no more than 3.  Like intervals, the lowest note in the chord is called the root or tonic.

The simplest chords are two note chords.  Their chord names match the corresponding interval name.  For example, playing the chord C and E is called a Major 3rd (interval count 4).  The chord C and G is a Perfect 5th (interval count 7).  Of course, a chord may begin (its root or tonic) on any note.

Three note chords are known as triads and can be defined by two interval counts.  Let's look at one of the most played three note chords C-E-G.  You can view this chord as the two consecutive intervals C to E and E to G with intervals of 4 and 3 respectively.  The first interval count is 4, a Major 3rd.  The second interval count is 3, a minor 3rd.  Triads that start like this, a Major 3rd plus a minor 3rd, are called Major chords.  C-E-G is therefore called C Major because it's root is C.  Triads with the Major and minor intervals reversed,  are called minor chords.  An example is D minor, D-F-A.   In this course, we'll stick with Major chords.


One final comment on the terms Major (M usually capitalized) and minor (m usually not capitalized):  these are like some other music terms that mean different things depending on the context.  In this lesson, these two terms relate to interval counts as well as to chords.  Hopefully you remember from the earlier lesson on scales that they can also be applied to them.  So context is everything and the exact meaning of the terms varies but they are all related to intervals.

summary of terms you should know

other terms you are likely to encounter

Knowing something about these will minimize the amount of time your eyes glaze over when talking to other musicians: