Jam JamMusic theory glossary
This glossary defines the music theory terms you meet while playing: chords, scales, tuning, rhythm and file formats. Each entry gives a direct definition, an explanation, a concrete example and a link to the Jam Jam tool that shows the idea on screen or by ear.
Chord
A chord is a set of at least three notes played together, built on a base note called the root.
Its quality (major, minor, seventh, suspended…) depends on the intervals stacked on the root. Jam Jam’s chord detection recognises 14 qualities on the 12 roots, 168 chords in all.
Example C major combines C, E and G; A minor (Am) combines A, C and E.
Inversion
An inversion is a chord whose lowest note is not the root.
The notes stay the same, only the order changes: first inversion with the third in the bass, second with the fifth. Jam Jam’s chord catalogue shows, for each chord, its inversions and the chords that share the same notes.
Example C major with E in the bass is the first inversion of C, written C/E.
Slash chord
A slash chord is written with a slash: the chord on the left, the bass note on the right.
It marks an inversion or a bass note outside the chord, often for a descending bass line. Jam Jam reads and shows slash chords everywhere, in the songbook as in the diagrams.
Example G/B is played as a G major with B in the bass.
Voicing
A voicing is a precise way of laying out a chord’s notes on the instrument: which ones, at which octave, in which order.
One chord has several voicings, easier or brighter. On guitar, Jam Jam shows up to 6 positions per chord; on piano, 216 generated voicings (18 formulas on 12 roots).
Example C major as an open chord at the bottom of the neck, or as a barre at the 8th fret: same chord, two voicings.
Scale
A scale is a series of notes ordered by pitch, with a fixed pattern of steps, used as the pool for a melody or a harmony.
The major scale follows whole, whole, half, whole, whole, whole, half. The Jam Jam online keyboard can lock 16 scales, so you only play the notes that belong to it.
Example The C major scale: C, D, E, F, G, A, B.
Mode
A mode is a scale obtained by starting from another degree of the major scale, which changes its colour.
Dorian sounds minor with a major sixth, Phrygian minor with a minor second, Mixolydian major with a minor seventh. These three modes are among the 16 scales of the Jam Jam keyboard.
Example D Dorian uses the notes of C major, but starting from D.
Pentatonic
A pentatonic scale has only five notes per octave.
The minor pentatonic (root, minor third, fourth, fifth, minor seventh) is the basis of rock and blues improvisation; the blues scale adds a diminished fifth. Jam Jam offers the minor pentatonic and the blues scale.
Example A minor pentatonic: A, C, D, E, G.
Key
The key of a piece is its home note (the tonic) and the major or minor scale it draws its notes from.
Knowing the key tells you which chords are likely to appear. Jam Jam’s chord detection estimates a piece’s key along with its chords.
Example A song in G major often revolves around G, C, D and Em.
Relative minor
The relative minor of a major key is the minor key that uses exactly the same notes, a minor third lower.
Both share the same key signature; only the home note changes. You find it three semitones below the major tonic.
Example A minor is the relative of C major; E minor that of G major.
Transposition
Transposing means moving a whole piece up or down by the same number of semitones.
You transpose to fit a song to your voice or instrument; the intervals stay identical. The Jam Jam songbook transposes chords, key, melody and diagrams from −6 to +6 semitones, never the lyrics.
Example G, C, D transposed by +2 become A, D, E.
Capo
A capo is a clamp placed on the neck that shortens every string and raises the instrument by as many semitones as frets.
It lets you keep easy chord shapes in a higher key. The Jam Jam songbook suggests a capo fret, chosen from the real difficulty of the shapes.
Example Capo on the 2nd fret, the G shape sounds A.
Semitone
A semitone is the smallest step between two notes in Western music: one key to the next on a keyboard, one fret to the next on a guitar.
An octave has twelve semitones, two semitones make a whole tone. It is the unit of transposition and of the capo.
Example E and F, or B and C, are only one semitone apart.
Alternate tuning
An alternate tuning is any way of tuning a string instrument other than standard tuning.
It makes certain chords easier or gives lower open strings. The Jam Jam tuner offers 79 tunings across 21 instruments.
Example Drop D (D, A, D, G, B, E): the low E string drops a whole tone.
Cent
A cent is a unit of pitch equal to one hundredth of a semitone.
Tuners use it to say how far a note is sharp or flat. The Jam Jam tuner considers a string in tune within ±5 cents.
Example A string at +20 cents is slightly too tight: loosen it a little.
A440 (concert pitch)
A440 is the reference frequency of the A above middle C (A4), to which most instruments are tuned.
Every other frequency follows from it: one semitone multiplies the frequency by the twelfth root of 2. Some orchestras tune higher; the Jam Jam web tuner offers 415, 432, 440, 442 and 443 Hz or a custom value.
Example With A4 at 440 Hz, the guitar’s low E is 82.41 Hz.
Re-entrant tuning
A re-entrant tuning places one string higher than its neighbour instead of running from low to high.
It is the ukulele’s standard tuning: the G string is tuned high, which gives its bright sound. Jam Jam’s ukulele tuner offers re-entrant standard, Low G and baritone.
Example Ukulele G, C, E, A with a high G: the first string is higher than the second.
Tablature
Tablature writes music by strings and frets rather than as notes on a staff.
Each line stands for a string, each number for the fret to press. Jam Jam shows a melody as tablature as well as on a staff, adapted to the chosen instrument.
Example A 3 on the lowest line of a guitar tab: 3rd fret of the low E string, a G.
Fixed-do solfège
Fixed-do solfège names the notes do, re, mi, fa, sol, la, si, with do always equal to C, whatever the key.
It is the system of French-, Italian- and Spanish-speaking countries; English-speaking countries use the letters A to G. Jam Jam shows notes as letters or solfège, as you choose in the settings.
Example Sol in fixed-do solfège is G in English notation.
Tempo and BPM
Tempo is the speed of a piece; it is measured in BPM, beats per minute.
At 60 BPM, one beat falls every second; at 120 BPM, two per second. The Jam Jam metronome beats the tempo you choose, inside the online keyboard.
Example A ballad often sits between 60 and 80 BPM.
MIDI velocity
MIDI velocity is how hard a key is struck, sent by the keyboard as a number from 1 to 127.
The sound uses it to play louder or softer. The Jam Jam online MIDI keyboard reads each note’s velocity, in normal, inverted or fixed mode.
Example A lightly touched key sends a low velocity, around 20; a struck key, over 100.
ChordPro
ChordPro is a text format for songs: chords are written in square brackets inside the lyrics.
Directives in curly braces add the title, artist or sections. Jam Jam imports ChordPro files and exports a songbook song as ChordPro (.cho).
Example {title: Amazing Grace} then [G]Amazing [C]grace.