Optical Digital Theremin with Audio Synthesis and Graphic Interface

he theremin is one of the first elec- tronic musical instruments and one of the few played without physical contact since it only re- quires hand and finger movements to control the amplitude and frequency of the musical note. However, the capacitive functioning of the anten- nas increases the sensitivity to electrical interfer- ence, its timbre is fixed, and the frequency an- tenna's vertical arrangement could limit the use of people with amputated fingers. Furthermore, it does not contain any help to guide the execu- tion, which makes it a very difficult instrument to play. In this paper, we present the development of a digital optical theremin with an audio syn- thesis process, intuitive graphical interface, frequency antenna in the horizontal position, and linearization of the frequency-distance relationship. These features are intended to aid learn- ing and interpretation of the instrument and ex- tend access to people with finger limitations. In order to validate the instrument's behavior and characteristics, we conducted three experiments: 1) accuracy analysis of the linearization through the mean absolute error in units of cents and the Kruskal-Wallis statistical inference test, 2) val- idation of the steps of the audio synthesis mod- ule, and 3) checking of the timbral diversity, both through the Fourier spectrum. This prototype could be used as an auxiliary tool in musical initi- ation and the development of musical perception.