Physical Interfaces and Electonic Arts (Bongers 2000)

In Physical Interfaces and Electronic Arts, Bongers follows the historical development of physical interfaces with the advent of electronic art forms, focusing on electronic music. He describes how these interfaces have evolved with advancements in sensors. The design of instrument interfaces became no longer constrained by the sound desired. For example, a violin shape is not necessary to produce digital violin sounds, allowing designers to create more ergonomic or human-centered instruments. One shortcoming, however, that designers seek to address is a lack of tactual feedback to music players in terms of what is felt and the sounds produced. Bongers describes three kinds of interactions, "performer-system (e.g. a musician play an intstrument), system-audience (e.g. installation art), and performer-system-audience." He criticizes that many supposedly 'interactive' systems are actually 'reactive' systems, and that instead humans and systems should influence each other.

Bongers also goes into depth about the mechanics of digital sound and sensing technologies, using several examples of digital instruments from his research. Sensors translate "physical energy (from the outside world) into electricity (into the machine world)". Actuators perform the opposite function. Some examples of sensors are: kinetic (pressure, torque, inertia), light, sound, temperature, smell, humidity, electricity, magnetism, and electro-magnetism (radio waves). Some examples of human modalities that would be read are muscle action, blowing, voice, blood pressure, and heart rate. Bongers' taxonomy of movements is as follows: Muscle action - either isometric (pressure) or movement (displacement). Movement - either mechanical contact (rotary pots/dials) or contactless (ultrasound, motion sensors)