The means and manner by which a human may interact with a machine for the purpose of music making has proven an area of immense research and activity since the days of early electronic instruments. This term is used without any great consistency, in part due to the immense scale of current research and activity in the field.
Any conceivable means of inputting data into a system to elicit some form of musically meaningful response may be considered to be a controller. In the broadest possible sense, a controller, via some form of communication between component parts (e.g. MIDI, converters, computer software) in conjunction with some means of producing or modifying sound may be termed an Interactive Instrument. Frequently, such controllers exist in homologous relationships with sensors (e.g. of movement). Thus gloves, conductors batons, toys, amongst countless other examples, may be constructed or modified to function as musical instruments.
An existing form of musical instrument may be modified through the addition of sensors, enabling control of additional electronically mediated sound generation or modification (including the instrumental sound itself) in addition to the conventional control the musician exerts over the production of the acoustic sound. Such examples are also sometimes referred to as Extended Instruments.
See also:Controller, Data Tracking, E- and I-instruments, Gesture Capture, Interactivity, Interface, Live Electronics, MIDI, Movement Detection, Pitch-to-MIDI, Sensor