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Lawrence Casserley

Vista Clara

Piano and ringmodulation

Vista Clara was composed for the Venezuelan pianist Clara Rodriguez, who gave the first performances in 1983. The work consists of 21 structures, which form a set of variations. Each structure is divided into seven subsections consisting of 2, 3, 3, 3, 3, 2, and 2 bars. These are indicated in the score by using dotted bar lines at the end of bars, solid bar lines at the end of subsections and double bar lines at the end of structures. On a larger scale there are two superimposed structural organisations into 3 × 7 structures and 7 × 3 structures. These are indicated by triple bar lines after structures 3, 6, 7, 9, 12, 14, 15, and 18. Each marks a signiWcant change in direction for the piece.
The piano sound is ring modulated throughout, with a new modulation frequency at each subsection (solid) bar line. The modulation frequencies comprise an equally tempered scale of 21 notes per octave. The 21 pitches are spread across a seven octave range and numbered from lowest to highest:
1 = 21.0 Hz
2 = 26.0 Hz
3 = 32.7 Hz
4 = 45.5 Hz
5 = 57.3 Hz
6 = 72.2 Hz
7 = 100.5 Hz
8 = 126.6 Hz
9 = 159.5 Hz
10 = 176.1 Hz
11 = 222.0 Hz
12 = 279.0 Hz
13 = 389.0 Hz
14 = 490.0 Hz
15 = 617.0 Hz
16 = 681.0 Hz
17 = 859.0 Hz
18 = 1082.0 Hz
19 = 1505.0 Hz
20 = 1896.0 Hz
21 = 2389.0 Hz
These numbers appear in circles above the small stave at the beginning of each subsection and indicate the required modulation frequency, which is also shown as a notated pitch. The number above each note shows the number of cents above or below the notated pitch. The changes must occur exactly on the down beat of the bar at which they are indicated.
The pitches played by the piano are derived from a ‘closest fit’ to the seven-note-per-octave scale, which produces a symmetrical (Dorian) mode. This is clearest in the opening structure. The degree of ‘error’ between the two scales determines much of the resulting ring modulated sound.
But I like to describe Vista Clara in quite another way. In the English landscape garden of the 18th century much use was made of a device called a ha- ha, a ditch designed so that the garden appeared to continue uninterrupted into the surrounding landscape, yet it prevented the cattle from invading the garden and trampling on the flower beds. Long vistas could be made, often with a distant obelisk or gothic ruin at the end. Vista Clara is a bit like this – it sets off determinedly in a certain direction, only to Wnd the apparent end of the vista blocked by a ha-ha; so it turns and strikes oV in a new direction toward a new vista. After several such twists and turns it tries to return to where it started, but there is another ha-ha, and that way too is blocked.
Lawrence Casserley January 2003

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