atonal music
music that does not have a tonic, or tonal center. Such music will sound dissonant to the average listener, but in fact the concept of dissonance or consonance simply doesn’t apply, since there is no “home key” to resolve to. Pure atonality is rare in jazz, but musicians nevertheless often use free improvisation, which approximates atonality in its emphasis on elements other than harmony (timbre, melodic intervals, rhythm).
backbeat
a consistent accent on beats 2 and 4 of a measure. The backbeat produces a rhythmic layer that contrasts with the usual accenting of beat 1 (the downbeat) and beat 3 in the underlying meter.
ballad
a slow, romantic popular song.
bar
a rhythmic unit, lasting from one downbeat to the next. Also known as a measure. In written music, a bar is marked off by vertical lines known as bar lines.
block-chord texture
a subset of homophonic texture in which the pitches of the accompanying harmony move in exactly the same rhythm as the main melody. Block-chord texture is typically found in big-band jazz, as, for example, when a saxophone section plays and simultaneously harmonizes a melody. See also soli.
blue notes
notes created through variable intonation.
boogie-woogie
a blues piano style in which the left hand plays a rhythmic ostinato (i.e., repeated pattern) of eight beats to the bar. For musical examples, see assignment on Kansas City Jazz.
brass instruments
wind instruments played with a cup-shaped mouthpiece. This category includes the trumpet, cornet, trombone, and tuba.
break
a brief passage (usually 2 to 4 bars) in which the prevailing texture (whether homophonic or polyphonic) is interrupted by monophonic texture.
bridge
the middle part of an AABA form — i.e., the “B” part. Musicians sometimes also call it the “channel.” Its function is to connect, or “bridge,” between the “A” sections.
cadence
stopping places, usually associated with tonic and dominant chords, that divide a harmonic progression into comprehensible phrases.
cadenza
(term from classical music): a virtuoso passage for a single instrument, usually monophonic.
chart
a shorthand musical score that serves as the point of reference for a jazz performance. Often, only the harmonic progression is specified. Also known as a lead sheet.
changes
jazz slang for harmonic progression.
chord substitutions
substituting one chord, or a series of chords, for harmonies in a harmonic progression.
chorus
a single statement of the harmonic/rhythmic cycle defined by musical form (e.g., 12-bar blues, or 32-bar popular song form).
chromatic harmony
harmony that draws upon the 12-note chromatic scale, as opposed to the more “normal” 7-note diatonic scales (major or minor, e.g.)
chromatic scale
the scale containing twelve equally spaced notes within the octave, corresponding to all the keys (black and white) on the piano.
comping
playing chords in a rhythmically unpredictable fashion as accompaniment for an improvising soloist. Comping is an important way for the harmony instruments in the rhythm section (e.g., piano, guitar) to add a contrasting rhythmic layer.
consonance (adj.: consonant)
harmonies that are stable (i.e., that do not need to resolve to another harmony).
countermelody
(also known as an obbligato). In a piece whose texture consists clearly of a melody with accompaniment (i.e., a homophonic texture): a countermelody is an accompanying part with distinct, though subordinate, melodic interest. If the melodic interest were not subordinate, the texture would be polyphonic: two or more melodies of more or less equal melodic importance.
counterpoint (adj: contrapuntal)
two or more melodic lines of equal importance (i.e., polyphonic texture), especially when composed.