Lessons · Musicianship

Accompaniment patterns

Block, Alberti, oom-pah, wash, ostinato

% One eight-bar period over one progression — I vi ii V | I IV V I —
% and from here down only the left hand changes. BLOCK chords first,
% the whole bar in a single stack, so all the motion belongs to the
% tune. That one stack serves all four chords: '@~-2' steps it down
% two degrees to vi, '@~1' up one to ii, '@~-3' down three to V —
% whichever step keeps it under the tune, which the consequent then
% takes up an octave along with the melody.
 
bpm 60
key c maj
 
Ante  ::= '1 _2 7 _2 5 _4 6 _2 5 _2 3 _4 2 _2 4 _2 6 _4 7 _2 6 _2 5 _4
Cons  ::= 5 _2 '1 _2 '3 _4 '4 _2 '3 _2 '1 _4 '2 _2 '1 _2 7 _4 '1 _8
Block ::= {.1, .3, .5, 1} _8
 
assert Ante[3:6] == Ante[0:3]@~-2
 
Ante Cons
{Ante, Block Block@~-2 Block@~1 Block@~-3}
{Cons, Block Block@~3 Block@~4 Block}
 
 
% Break that stack in TIME and the same harmony dances: the root alone
% on the strong beat, the rest of the chord off it — OOM-PAH, the whole
% nineteenth century's left hand. The bass alternates root and fifth an
% octave and more below the chord, so the two registers do two jobs.
 
Oom ::= ..1 _2 {.3, .5, 1} _2 ..5 _2 {.3, .5, 1} _2
 
{Ante, Oom Oom@~-2 Oom@~1 Oom@~-3}
{Cons, Oom Oom@~3 Oom@~4 Oom}
 
 
% ALBERTI breaks the chord in ORDER rather than in time: low, high,
% middle, high, twice a bar, never resting. It adds nothing to the
% harmony — .1 .3 .5 is exactly what Block stacks — and that is why it
% can idle under a tune for a whole movement. '*2' states the four-note
% cell twice; the assert spells out what that means.
 
Alberti ::= {.1 .5 .3 .5}*2
 
assert Alberti == .1 .5 .3 .5 .1 .5 .3 .5
 
{Ante, Alberti Alberti@~-2 Alberti@~1 Alberti@~-3}
{Cons, Alberti Alberti@~3 Alberti@~4 Alberti}
 
 
% Unroll the chord across two octaves instead and it stops being a
% pattern and becomes weather: up from the low root through the triad,
% back down through the fifth to the third, one note per unit. The
% pedal blurs the eight into one sonority — the trick BWV 846 runs for
% thirty-five bars — and under vi and V it reaches a1 and g1.
 
Wash ::= ..1 ..5 .1 .3 .5 1 .5 .3
 
{Ante, Wash Wash@~-2 Wash@~1 Wash@~-3}
{Cons, Wash Wash@~3 Wash@~4 Wash}
 
 
% An OSTINATO refuses to follow. This ground limps 3-2-3 against the
% tune's even halves and never transposes, so the harmony moves around
% it. Its three notes are the tonic triad: over I all three belong to
% the chord, over vi two, over IV and V one, over ii none — so the
% grind tightens and slackens while the bass sits perfectly still.
 
Ost ::= ..1 _3 ..5 _2 .3 _3
 
{Ante, Ost*4}
{Cons, Ost*4}
 
 
% The set entire, one piece: block chords state the period, oom-pah
% answers it, Alberti carries the sequence, the wash takes the climb to
% '4 at its widest spacing, the ground grinds one last antecedent, and
% Alberti closes onto a stack from c2 to c4.
 
{Ante, Block Block@~-2 Block@~1 Block@~-3}
{Cons, Oom Oom@~3 Oom@~4 Oom}
{Ante, Alberti Alberti@~-2 Alberti@~1 Alberti@~-3}
{Cons, Wash Wash@~3 Wash@~4 Wash}
{Ante, Ost*4}
{Cons, Alberti Alberti@~3 Alberti@~4 Alberti}
{..1, .1, .3, .5, 1} _8

% One eight-bar period over one progression — I vi ii V | I IV V I —
% and from here down only the left hand changes. BLOCK chords first,
% the whole bar in a single stack, so all the motion belongs to the
% tune. That one stack serves all four chords: '@~-2' steps it down
% two degrees to vi, '@~1' up one to ii, '@~-3' down three to V —
% whichever step keeps it under the tune, which the consequent then
% takes up an octave along with the melody.

bpm 60
key c maj

Ante  ::= '1 _2 7 _2 5 _4 6 _2 5 _2 3 _4 2 _2 4 _2 6 _4 7 _2 6 _2 5 _4
Cons  ::= 5 _2 '1 _2 '3 _4 '4 _2 '3 _2 '1 _4 '2 _2 '1 _2 7 _4 '1 _8
Block ::= {.1, .3, .5, 1} _8

assert Ante[3:6] == Ante[0:3]@~-2

Ante Cons
{Ante, Block Block@~-2 Block@~1 Block@~-3}
{Cons, Block Block@~3 Block@~4 Block}

% Break that stack in TIME and the same harmony dances: the root alone
% on the strong beat, the rest of the chord off it — OOM-PAH, the whole
% nineteenth century's left hand. The bass alternates root and fifth an
% octave and more below the chord, so the two registers do two jobs.

Oom ::= ..1 _2 {.3, .5, 1} _2 ..5 _2 {.3, .5, 1} _2

{Ante, Oom Oom@~-2 Oom@~1 Oom@~-3}
{Cons, Oom Oom@~3 Oom@~4 Oom}

% ALBERTI breaks the chord in ORDER rather than in time: low, high,
% middle, high, twice a bar, never resting. It adds nothing to the
% harmony — .1 .3 .5 is exactly what Block stacks — and that is why it
% can idle under a tune for a whole movement. '*2' states the four-note
% cell twice; the assert spells out what that means.

Alberti ::= {.1 .5 .3 .5}*2

assert Alberti == .1 .5 .3 .5 .1 .5 .3 .5

{Ante, Alberti Alberti@~-2 Alberti@~1 Alberti@~-3}
{Cons, Alberti Alberti@~3 Alberti@~4 Alberti}

% Unroll the chord across two octaves instead and it stops being a
% pattern and becomes weather: up from the low root through the triad,
% back down through the fifth to the third, one note per unit. The
% pedal blurs the eight into one sonority — the trick BWV 846 runs for
% thirty-five bars — and under vi and V it reaches a1 and g1.

Wash ::= ..1 ..5 .1 .3 .5 1 .5 .3

{Ante, Wash Wash@~-2 Wash@~1 Wash@~-3}
{Cons, Wash Wash@~3 Wash@~4 Wash}

% An OSTINATO refuses to follow. This ground limps 3-2-3 against the
% tune's even halves and never transposes, so the harmony moves around
% it. Its three notes are the tonic triad: over I all three belong to
% the chord, over vi two, over IV and V one, over ii none — so the
% grind tightens and slackens while the bass sits perfectly still.

Ost ::= ..1 _3 ..5 _2 .3 _3

{Ante, Ost*4}
{Cons, Ost*4}

% The set entire, one piece: block chords state the period, oom-pah
% answers it, Alberti carries the sequence, the wash takes the climb to
% '4 at its widest spacing, the ground grinds one last antecedent, and
% Alberti closes onto a stack from c2 to c4.

{Ante, Block Block@~-2 Block@~1 Block@~-3}
{Cons, Oom Oom@~3 Oom@~4 Oom}
{Ante, Alberti Alberti@~-2 Alberti@~1 Alberti@~-3}
{Cons, Wash Wash@~3 Wash@~4 Wash}
{Ante, Ost*4}
{Cons, Alberti Alberti@~3 Alberti@~4 Alberti}
{..1, .1, .3, .5, 1} _8

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Accompaniment patterns · Pattern Engine