Marco Donnarumma

The XTH Sense is a free and open biophysical musical instrument. It amplifies sounds from heart, blood and muscles of a performer’s body and uses them to create music, video or light in real-time. It was created by Donnarumma in 2010 and used ever since in all of his works, ranging from biophysical music concerts, actions art pieces, installations and dance-theater productions.

The principle at the core of the XTH Sense is to approach the human body as a complete instrument in itself, instead of “interfacing” the human body to an interactive system. The XTH Sense transcends the paradigm of the user interface in that it captures sonic matter and control data directly from the performer’s body. There is no apparent mediation between body movements and the resulting music because the raw sonic material originates within the fibres of the body, and the sound manipulations are driven by the vibrations of the performer’s muscle tissue.

During a performance, muscle movements and blood flow produce subcutaneous low frequency sound waves (technically known as mechanomyographic signals or MMG). Two microphone sensors capture the sound waves created by the performer’s body and send it to a computer. A dedicated software analyses the sound waves and thus understand the performer’s gesture and force levels. Then, according to this information, the software manipulates algorithmically the sound of the performer’s body and plays it back through loudspeakers.

The XTH Sense can be played as a traditional musical instrument, for instance, analog sounds can be produced and modified by adequately exciting the “chords” i.e. by contracting the muscles, and it can also be used as a gestural controller to drive audio synthesis or sample processing. The most interesting performance feature of such system consists in the possibility to expressively control a multi-layered processing of the MMG audio signal by simply exerting diverse amounts of kinetic energy.

For instance, stronger and wider gestures could be analysed and mapped so to generate sharp, higher resonating frequencies coupled with a very short reverb time, whereas weaker and more confined gestures could be deployed to produce gentle, lower resonances with longer reverb time. The form and color of the music is continuously shaped in real time with a very low latency (measured at 2.5ms), thus the interaction among the perceived sonic force and spatiality of the gesture is neat, transparent and fully expressive.

The XTH Sense is open source and open hardware, meaning that its software, the hardware documentation and tutorials to make and use the instrument are freely downloadable on-line. The XTH Sense is used by creatives ranging from performing artists and musicians, to researchers in physiotherapy and prosthetics, and universities and students in diverse fields.