piano practice - chords

You'll see chord symbols above each bar of standard notation.

It specifies a set of background notes that last roughly a bar. Maybe a couple bars, maybe only a beat. These background notes make a slowly moving setting for the melody to kind of dance around on top of. A chord usually has many of the melody notes in it.

Basic chords:

Chords start with a root note, then extra notes (usually 2) are played at the same time. Which extra notes? Depends on the chord's quality.
 Quality    Intervals     Notes
 Major      root +4 +7    C E  G
 Minor      root +3 +7    C Eb G
Those intervals are in "halfsteps". D to D# is a halfstep. C to G is 7 halfsteps. Count them out on the piano. Chords can start on any root note. Then you skip the number of halfsteps up to find the rest of the notes in the chord quality.

Chord "root" is the base of the chord.
Chord "quality" is the pattern of halfsteps for the extra notes.
Chord "bass" is the lowest note of a chord. Often but not always same as root. We'll see that a chord's notes' octaves can be anywhere.

Interval names

There are 12 halfsteps available within an octave (C to next C up). Each halfstep distance is an "interval" and has a name.
 halfstep    short    interval
 distance    name     name
 0           oct      unison - same dang note
 1           m2       minor 2nd
 2           2        2nd  (sometimes called a major 2nd)
 3           m3       minor 3rd
 4           3        3rd
 5           4        perfect 4th
 6           d5       tritone / augmented 4th / diminished 5th
 7           5        perfect 5th
 8           m6       minor 6th / augmented 5th
 9           6        6th
 10          m7       minor 7th
 11          7        7th
12 octave (oops, we started over) this is the same as unison
These names are a little confusing but come from the major and minor scales' layout.

A whole step is 2 halfsteps and is handy in defining the major and minor scale interval layouts.
 Major is  w w h w w w h
          1 2 3 4 5 6 7 1
          c d e f g a b c
Minor is w h w w w h w 1 2 3 4 5 6 7 1 a b c d e f g a
A melody usually sticks to these 7 most popular notes of the key signature.

Each interval has a characteristic sound. 2 notes ...
1 halfstep apart sound pretty grating and terrible.
a 5th apart sound pretty dang good due to being about a 3rd of an octave away from each other.

The octave (unison) interval sounds great. It sounds so great, that you can move the octave of any chord note to any other octave and you'll still hear the same chord.

Octaves don't matter

So an interval is a distance and octaves don't matter. What happens when we go down a perfect 5th from C? We get F which is a perfect 4th up from the C an octave down. Since octaves don't matter in chords, an interval of a 5th is a 4th with an octave swap. Since we can swap octaves, a "5th up" sounds very "4th down".

Inversion = Arrangement

The octaves of the chord's notes can be anywhere. Your ear still hears that chord quality regardless of the notes' octaves. It's still the same chord, but in a different "inversion". Let's take a C chord:
 C4 E4 G4        root position.
    E4 G4 C5     1st inversion.
       G4 C5 E5  2nd inversion.
 (4 note chords can have a 3rd inversion)
But since you can put those notes in any octave you please, referring to "inversions" is mostly only done by piano teachers. 1st and 2nd inversion are not nearly all the possibilities you've got.

Piano players say "chord arrangement", giving the root, quality, and octave layout.

Although you can use any octaves, it has to sound good. When you play notes too close together in the bass octaves, they sound "muddy", sort of overlapping each other - unclean... So keep bass notes spread out by an octave, 4th, or 5th in the bass.

Picking new octaves for chords can improve (and wreck) a song dramatically. It's a big part of a song's "arrangement". Picking chords and good inversions for them is an art.

Dominant 7th Chord aaand...

Some people just can't be satisfied. 3 Notes? Not enough for them. So we've got "dominant 7th" chords and other chord qualities...

For an extra (4th note) in the chord, pick an extra note that sounds good. A dominant 7th chord is where you take a major chord and add a minor 7th. So root +4 +7 +10 (or root,3,5,m7). That m7 interval gives you a yearning sound. It puts you on the edge of your seat wanting to hear the next chord. Play a G7 then a C (g dominant 7 chord, then c major chord). Sounds pretty great, huh?

But really, a dominant 7th chord is just another chord quality. There are quite a few popular chord qualities...

Mooore Chord Qualities

Jazz is big into naming all of the useful chords. And some un-useful ones. Here's a pretty decent list of chords and how to make them:
 name  halfstepList  alternateNames
       0,4,7         maj - so popular it's
                     quality is just "you know"
 5     0,7           1+5 "power chord"
                     only one with no 3rd
 m     0,3,7         min -
 dim   0,3,6         o
 aug   0,4,8         +
 sus   0,5,7         sus4
 sus2  0,2,7         1+2+5
 4     0,4,7,5       add
 2     0,4,7,2       add2 add9 Maj(9) Madd9
 6     0,4,7,9       maj6 M6
 m2    0,3,7,2       min(9) m(9)
 m6    0,3,7,9       min6
 7     0,4,7,10      dom7
 M7    0,4,7,11      Maj7
 m7    0,3,7,10      min7
 mM7   0,3,7,11      minMaj7
 dim7  0,3,6, 9
 m7b5  0,3,6,10      min7b5 hDim7 (slashes)
 7sus  0,5,7,10      7sus4
 7b5   0,4,6,10
 7#5   0,4,8,10      7aug
 M7#5  0,4,8,11      Maj7aug M7aug augM7
 7#11  0,4,7,10,6    7(#11)
 7,13  0,4,7,10,9    7(13) 7(add13)
 7b9   0,4,7,10,1    7(b9) b9
 7b13  0,4,7,10,8    7(b13)
 7#9   0,4,7,10,3    7(#9)
 9     0,4,7,10,2    7(9)
 M7#11 0,4,7,11,6    Maj7(#11) M7(#11)
 M9    0,4,7,11,2    Maj7(9) 7(9) maj9
 6,9   0,4,7, 9,2    Maj6(9) 6(9)
 m9    0,3,7,10,2    min7(9) m7(9)
 m7,11 0,3,7,10,5    min7(11) m7(11)
 mM7,9 0,3,7,11,2    minMaj7(9) mM7(9)
 9sus  0,5,7,10,2    9sus4
 11    0,4,7,10,2,5
 13    0,4,7,10,2,5,9

Altered Chords

Chords can also be tweaked by
suspended. Taking away notes - "suspended 5th".
altered. Changing notes - "altered 3rd". If you alter it up a half step, it's "augmented". If you alter it down a half step, it's "diminished".
added. Adding notes ("added 6th")

It's a freakin' mess I tell ya !!

Slash Chords

Pop guys just kind of say "who cares what it's called - it sounds GOOD". They tack extra notes into the bass via "slash chord" notation.

So C/D means play a C major and add a D note into the bass. Far enough down that the whole thing doesn't sound "muddy".

Is the D the actual chord root or is the C??? Pop composers just don't care. If it's a chord that sounds good, it's a good chord !! Play the dang thing. Leave categorizing it to the jazz dudes...

Chord Progressions

Going from one chord to the next is called a "chord progression". Or, if you're a jazz dude, called "the changes". As I mentioned, chords are a slowly moving landscape for a melody line to sort of dance on top of.

So especially in pop music, some songs keep the chords simple (I'm looking at you "the blues") and the same sequence of chords is reused from song to song. This is great for the listener that doesn't want to have to think. Maybe you had a long day.

Also, keeping the note jumps small when going to the next chord makes it sound way better. This is called "voice leading" and is too big a topic for right here.

Time to learn a little 'bout midi?