Gordon Monro - What Are You Really Thinking?
"What are You Really Thinking?" is a sonification of brainwave data which was posted as a challenge to artists and scientists in connection with the International Conference on Auditory Display held in Sydney in July 2004. The constraints were that the data had to be mapped in a systematic way into sound, and that the data had to be used at the rate of one second per second (no speeding up, slowing down, or re-ordering). There were 26 channels of brainwave data from 26 electrodes placed on the subject's scalp, and an additional 10 channels of data recording, heartbeat, respiration, eye muscle movement, etc.
The subject was listening to a piece of music; the identity of the piece was kept secret until the conference, so was not known to the composers. It was in fact by David Page, part of the soundtrack for the Bangarra Dance Company work "Fish".
In "What are You Really Thinking?", each channel from the scalp was used as a sound source. It was analysed into narrow frequency bands, and activity in a specific band caused a musical note to sound with a frequency 30 times that in the data; for example activity at 10 cycles per second would cause a note with frequency 300 cycles per second. Each note has a waveform consisting of narrow triangular pulses.
The sounds generated from the scalp electrode data were modified by the data from the other channels:
(*) The eye movement data controlled panning of the data from electrodes near the front of the head.
(*) A high signal from the Orbicularis Oculi signal (supposed to indicate "startle") caused the sounds to become noisy.
(*) A high signal from the jaw muscle channel caused a nasal quality in the sound.
(*) The respiration signal affected the reverberation.
In addition the heart-beat sound was mixed in, in a way controlled by the skin conductance data.
The piece ends with some sounds from the outside world, as a reminder that despite the large amount of data available in the brainwave recordings, we still have no access to the subject's thoughts.