Milwaukee, Wisconsin experimental musician and visual artist Wilhelm Matthies is well-known for creating graphic scores of elegant design and legibility; these often feature fine brushwork and a grisaille palette that recalls East Asian ink painting. He also is the creator of a family of string instruments he calls mosesa, which he has been developing since 2012. The mosesa resembles something along the lines of a minimalist zither with flexible planking and resonating materials of various types, originally, plastic bottles; Matthies usually plays with a violin or erhu bow but the instrument can also be played directly with the hands. The mosesa featured on Curtains is the mosesa 9-CedarPlate, an instrument that employs cedar as its resonating material and features a single bridge (earlier versions of the mosesa had two bridges); in addition, Matthies augmented the basic sound of the mosesa with a chain of guitar pedals.
For the Jefferson Park set, Matthies interpreted his graphic score GC 1-19-18 (3). The most striking thing about the performance is the range of voices Matthies is able to elicit. Timbre predominates over pitch—the latter is rarely fixed and generally appears as a continuous gamut of microtonal shades, which Matthies produces through string-bending and bow articulation. At times this gives the mosesa a vina-like sound (the compass is reminiscent of the vina as well); at other times, it recalls the scratch and whine of the erhu. There is a vocal quality to much of the sound, a waxing and waning of range and intensity that mimics the dynamic cycle of an emotion; the electronic pedals serve to alter the textures and enhance the already considerable color variety inherent in the instrument alone.