P300 Harmonies: A Brain-Computer Musical Interface

We present P300 harmonies: a P300-based Brain-Computer Musical Interface. Using a commercial low-cost EEG device, the user can voluntarily change the harmony of an arpeggio by focusing and mentally counting the occurrences of each note. The arpeggio consists of 6 notes separated by an interval of 175ms. The notes of the arpeggio are controlled through 6 switches, where each switch has two possible states: up and down. When a switch is in the up-state the note produced by this switch is one tone or semitone -depending on the switchhigher than when in the downstate. By focusing on each of the notes of the arpeggio, the user may change -after 12 repetitionsthe state of the corresponding switch. The notes of the arpeggio appear in a random order. The state of each switch is shown on a screen. Each switch flashes when the corresponding note is heard. The user can either focus exclusively on the auditory presentation or make use of the visual presentation as well. The interface was presented in a live performance, where the user was able to successfully change the state of all switches with 100% accuracy. An additional preliminary evaluation was performed with 3 more users, in which the selection accuracy was 83.33%.