Pitch class

Click this icon to see all possible E notes  (we call these the “pitch class E“)  on “guitar”.

Semitone, Octave

When one frequency is double another, these two are an octave apart.   Any octave divides into 12 semitones. On piano, key N+1 creates a frequency 1.059 times that of  key N.  These frequencies are a semitone apart.  Key N and N + 12 are an octave apart.  On guitar, on the same string, the notes created at frets N and N+1 are a semitone apart.  Frets N and N+12, an octave apart.

Interval

When two notes are played together (two singers, two notes on a guitar, two instruments …), we call this an interval. Depending on the semitone distance between them, we get different sound flavours, unique to that distance.

Major scale

Starting at some arbitrary note, major scale notes are 0, 2, 4, 5, 7, 9, 11 semitones above it .  Each of these seven notes is called a scale degree.  The first scale degree is called the tonic.  Each degree is also given a Roman numeral from I (the tonic) to VII, used in chord progressions.  The pitch classes of each of these notes make up all available notes for this major scale.

Click this icon to see a couple of octaves of E major along the bass string.

If we change the tonic (drag the anchor to the 1st fret (F2), say, on the bass string, all the notes change, but the intervals between each note and the tonic don’t change and keep their unique sound flavours (such as the sound created by the tonic and the third scale note) which we recognise, just “higher” or “lower”. This is the secret to reducing the memorisation effort, and building a mental framework to tie music concepts together. Your brain recognises these distances from a note that stands out from all the others. By making the tonic stand out, we hear the intervals made with it.  Thi is discussed in section “Using the scale”.

In music theory, the intervals made with the tonic and each  major scale note within an octave above the tonic  are called:  unison, major 2nd, major 3rd, perfect 4th, perfect 5th, major 6th, major 7th.  They are given equivalent numbers, shown in scale diagrams.  These are 1, 2, 3, 4, 5, 6, 7. Emuso can show these, or semitones from a tonic note, or note names.  The “Labels” button on the interval strip cycles through these and a few others.

Different scale types will differ in the intervals they require, and theory gives these names also, such as “minor 3rd”, “augmented 5th”.  We’ll look at these another time.

Pitch classes for any scale type show the same labels for the entire instrument.

Chord member intervals include the above, and additional intervals such as “minor 9th”.

Click this icon to see C major in region 4 (tonic on 5th and 3rd strings), with scale theory interval numbers. You are asked to lay this out along the 5th string.

The most common way chords are built uses the “Choose-skip” rule (emuso’s informal name). We’ll see and hear this, with the above layout,  in action below.

1. Choose a scale note.  Skip the next higher scale note.
2. Repeat 1 until you have chosen some number of scale notes.

Choose-skip three notes gets a triad. There are three different types of triad in the major scale. Choose-skip four notes gets a seventh (a triad plus next chosen scale note).  There are four different types of seventh chords in the major scale.  Beyond four notes, we get various chords, known as extensions.

Chord root

The first note of any of the above chords is called the root of the chord.

The above says nothing on how to create chord voicings with these notes (where to layout these notes on-instrument, and whether the root is in the bass or one of the other notes)

Visualising choose-skip

Press “Labels” until you see 1 – 7 repeated along the 5th string.  Select “Harmonic”on the Play Construct tool (under the toolkit button block).
Hold the ALT- key (opt- on Mac) and move the mouse over any scale note. You see and hear three different triad types (major rooted at 1,4,and 5.  minor rooted at 2,4, and 6. diminished  rooted at 7).  Notice the chord type and Roman numeral appear top-left of the guitar, while ALT is held down.

Now use the “Gen” dropdown (in the toolkit button block) and choose “Generate sevenths”, and repeat the above with ALT- and the mouse.  Some beautiful sounds.  There are four different types of “seventh” chords (major 7th rooted at 1 and 4. minor 7th rooted at 2,3, and 6. dominant 7th rooted at 5.  minor 7b5 rooted at 7)

Example voicings

Click “Chord-X” (in the toolkit button block).  While holding down CTL, click on each scale note.  The chord plays briefly.  (You can perform CTL+click each time). Exit the toolkit when done.  Usually chords from Chord-X are imprinted into a rhythm track in Rhythm-X to create a progression for practice.

Chord names and symbols

Emuso uses the Berklee convention (The Berklee Book of Jazz Harmony, by Joe Mulholland and Tom Hojnacki).

major triad: no symbol.  C for C major triad (except we show “maj” with ALT usage)
minor triad: “–“.  D- for D minor triad (except we show “min” with ALT usage)
diminished triad: “o“.  Bo for B diminished triad
major 7th: “maj7“. Cmaj7
minor 7th: “-7“. D-7
dominant 7th: “7“. G7
minor 7b5: -7(b5).  B-7(b5)

Intervals that determine the tonic for the scale, and its basic major “flavour”

To establish the sound flavour as major scale, notes chosen from the pitch classes of note 1 (tonic) need the most emphasis, along with notes chosen from the pitch classes of notes 4 and 7 semitones above the tonic.

For C major, emphasise notes in the pitch classes for C, E, and G.

Here’s one possibility for playing C major in a small region of the neck,  built around 5th string, fret 3.

At the bass end, we have three notes named A0, A0#, and B0.  After that we have seven repeated blocks of 12 notes, followed by one note, C8.

Each of these 12-note blocks starts with the note C, for example C1.

Seven of the notes are known as the natural notes. In block 1, these are C1, D1, E1, F1, G1, A1, B1

The remaining five note names include a # (sharp) sign.  In block 1, these are C1#, D1#, F1#, G1#, A1#.

Altogether, we get C1, C1#, D1, D1#, E1, F1, F1#, G1, G1#, A1, A1#, B1 in block 1.  Each note is one semitone higher in frequency than its predecessor.  So, C1# is a semitone higher than C1, and so on.

Block 2 then follows, with C2 being 12 semitones higher than C1.  We say C2 is an octave above C1.  Likewise, C2# is 12 semitones higher than C1#.  Blocks repeat all the way up to block 7. The last named musical note is C8, which is an octave higher than C7.

On guitar, if we wanted to play all the notes of one block, we’d do this using a few strings, otheriwise the hand movement is excessive, whereas this is feasible on piano.