Touch instruments [touch-sensitive instruments]
- Anne Beetem Acker
Electronic instruments that respond to the location and sometimes the degree of pressure of the user’s fingers. Touch instruments, or touch instrument applications, are based upon software implemented on electronic visual displays, also known as touchscreens. Touchscreens detect the position of finger or stylus contact with the display area. Examples include Bebot, a touch synthesizer first released in 2008 by Russell Black for Normalware that features four-finger multi-touch polyphony and user-definable behaviour including sound-generation methods, delays, and either continuous pitch changes or various discrete scales. Pitch is determined by the horizontal position of the finger on the screen, while timbre or loudness is controlled by the vertical position. The touch instrument applications Pianist and Guitarist introduced by MooCowMusic Ltd in 2008, function as wireless MIDI digital instrument simulators, with keyboards, guitar necks, or tablature displayed on touchscreens that are played with the fingers.
Some touchscreens can also detect the degree of pressure, such as a screen made by Touchco Inc. used for the Linnstrument introduced in 2010 by Roger Linn. On this polyphonic instrument, finger pressure determines note volume, strike velocity determines the volume of percussive sounds, finger left/right position determines pitch, and the forward/back position determines note timbre. The screen can display a variety of typical instrument interfaces such as keyboards or guitar frets, or can display a hexagonal pattern programmed to respond in different ways.
The term ‘touch-sensitive’ is sometimes used to describe instruments more correctly identified as ‘pressure-sensitive’ or ‘velocity-sensitive’. In pressure-sensitive devices, the control voltage varies with the degree of pressure applied to a key or touch-plate. Some keyboards of this type recognize discrete levels of pressure, while others produce a signal that varies continuously with changing pressure. In ‘velocity-sensitive’ keyboards, the control voltage varies with the speed at which the key is depressed.