Adaptive mapping for improved pitch accuracy on touch user interfaces

International audienceTouch user interfaces such as touchpad or pen tablet are often used for continuous pitch control in synthesis devices. Usually, pitch is set at the contact point on the interface, thus introducing possible pitch inaccuracies at the note onset. This paper proposes a new algorithm, based on an adaptive attraction mapping, for improving initial pitch accuracy with touch user interfaces with continuous control. At each new contact on the interface, the algorithm adjusts the mapping to produce the most likely targeted note of the scale in the vicinity of the contact point. Then, pitch remains continuously adjustable as long as the contact is maintained, allowing for vibrato, portamento and other subtle melodic control. The results of experiments comparing the users pitch accuracy with and without the help of the algorithm show that such a correction enables to play sharply in tune at the contact with the interface, regardless the musical background of the player. Therefore, the dynamic mapping algorithm allows for a clean and accurate attack when playing touch user interfaces for controlling continuous pitch instruments like voice synthesizers