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A project by Massimiliano Peretti

with the collaboration of the musician Simone Merli


a real-time audio-visual processing through biofeedback technology


The individual’s mode of reaction and interaction is related to the way individuals are reacting with and towards the surrounding environment, and its communicational language.


In the field of experimental psychology, neuropsychology and psychobiology, the process of tracking and recording cerebrum-cortical electrical activity, and its combination with other values of psychomotor activity, enables the diagnosis of the emotional responses of an individual.

Psycho physiological states are assigned to different electrical values. These variations in electrical potential can be recorded with the use of contact electrodes; in most academic situations they are connected to a signal amplifier and an inkjet instrument that reacts to the variations of potential and amplitude of the input data. This instrument, commonly known as electroencephalograph, has been the most important regarding studies on the functioning of cerebral activity during the awaken state of an individual, the sleeping state, emotional states, and during physiological and psychological disturbances. The recorded data, electroencephalogram, are permanent “memories” of a distinct period of cerebral activity.

There are other psychophysical data, related to human behaviors, which can be tracked together with variations in brain activity; these data are generally defined as biofeedback.

An important process in the studies of psychological states considers cardiac frequency, electro muscular activity (EMG), and body temperature. The interpretation of all these data gives a detailed response of the psychic activity of an individual.


EEG. By using an electroencephalograph and a digital interface we can make use of an electrical value, which is output by four sensors placed on the forehead, as a tracking guide of general brain activity. The signals are recorded in real-time and they vary according to psycho emotional variations in the individual, or according to mutations in the surrounding environment.

The average time for tracking and recording the data is seven minutes. The generated graph is based on a detailed interpretation of the four types of brain waves: alpha, beta, delta and theta. Their values are shown in amplitude (volt) and frequency (hertz), and isolated peaks of electrical activity: amplitude higher than hundred volts and low frequency, or short shocks of high frequency waves and small amplitude.


EMG. The electrical muscular response is recorded through the use of a dedicated sensor. Also in this case the signal gets digitized and elaborated by software that defines the thresholds of reaction of the individual and that compares the output data. We take in consideration the area related to facial muscles, particularly the forehead and eyebrows, as they tend to have a more sensitive reaction to emotional activation.


Cardiac Frequency. The heart beat is recorded through a frequency sensor placed on the index finger of the left hand, and its data is monitored and recorded through the whole duration of the experience.


Body Temperature. A temperature sensor is placed on the palm of the right hand and communicates to the biofeedback machine through recording of micro thermal variations.



The voltage values tracked by the biofeedback machine, when a tester is exposed to an emotionally stimulating video input, run through a sensors’ interface and are transmitted to a computer. The parameters related to the sound manipulation process, are directly and proportionally related to parameters of brain wave variations in the individual, which is exposed to the visual perceptive stimulation.

According to levels of acquaintance in the individual towards the sound environments being produced, the biofeedback machine tracks other emotional variations that are fed back into the video sequence, creating an interaction loop between the individual, the audio and the video. This process allows the tester to learn his/her emotional delivery according to the input provided through audio and video.