Block chord
A chord whose notes sound simultaneously.
What it means
A block chord — in German Blockakkord — is a chord whose notes are struck simultaneously, in contrast to the break, in which they sound one after another. The English expression comes from jazz and there denotes additionally a particular textural technique: the melody is underlaid with chord notes in close position, so that it appears as a dense, parallel-led mass of sound.
Musical use
In the general sense the block chord is the plainest form of setting a harmony and is omnipresent in chorales, accompaniments and homophonic textures. It stresses the combined sound and the rhythmic; where it is strongly accented, a percussive effect arises.
In jazz the designation means beyond this a particular piano and arranging technique. The melody lies on top and is accompanied by chord notes in close position beneath, frequently with an additional doubling of the melody an octave lower, so that both hands form a closed block that moves along with the melody. Passing notes of the melody are harmonised with sonorities of their own, usually diminished, so that every melody note receives a full chord. The result sounds dense and orchestral and is a transfer of wind-band writing to the piano.
The block chord is to be distinguished from chord breaking, which dissolves the same sonority into motion, and from contrapuntal texture, in which the voices are led independently.
This manner of playing is also known as locked hands; it goes back to the pianist Milt Buckner in the 1940s and 1950s and influenced, among others, George Shearing, Red Garland and Oscar Peterson.
Performance practice
With block chords see that all the notes really speak together — a slightly displaced note stands out clearly. Give the upper voice a little more weight, so that the melody lies above the sonority. And with dense positions check the balance; closely set low notes quickly sound murky.