Hyperacoustic instruments: Computer-controlled instruments that are not electrophones

This paper describes a musical instrument consisting of a physical process that acoustically generates sound from the material world (i.e. sound derived from matter such as solid, liquid, gas, or plasma) which is modified by a secondary in-put from the informatic world. This informatic input selects attributes such as the frequency range of the musical note be-ing sounded, while the acoustic process is kept in close con-tact with the user, to ensure a high degree of expressivity. In one example, ice skates with acoustic pickups are used to play music while the skater simultaneously controls a bandpass fil-ter with a hand-held keyer and wearable computer. Each skate works much like the bow on a violin, allowing the player to hit, scrape, rub, or “bow”, the ice in various ways to create a wide variety of musical textures. Additionally the player can select sound samples on a per-note basis and then “scratch” out a melody or harmony (playing multiple samples at once) on the ice on the rink like a team of Disk Jockeys (DJs) work-ing together to “scratch ” an array of vinyl records. Because the grooves on an ice rink are made by the player in a freeform fashion, there is much more room for variations in musical timbres and textures than with the fixed grooves of a record. Rather than merely using the keyer to trigger musical notes through MIDI note on/note off commands, we create acoustic sound through a physical process such as skating, and then turn those physical sounds into musical notes with the handheld keyer that functions as a modifier input. This combination combines the expressivity of non-electrophonic musical instruments like the violin with the flexibility of electrophones like the sound synthesizer. As a further contribution of the paper, a general taxonomy of acoustic transducers and a link to physical organology is provided, in which the top-level of the taxonomy is the state-of-matter in which the transducer operates