The UNVEILED PRESENCE (secret sounds 3) project makes use of the sound library of laser Doppler vibrometer recordings made in Helsinki in May 2010. A laser Doppler vibrometer can convert solid-state vibrations into a digital audio signal through a light beam and functions as an extremely focused accelerometer, similar to a very long cardioid microphone. Video recordings made of the vibration points were acoustically recorded, thus forming a visual reference to the sound. Based on this library of audio-visual recordings, a single-channel video composition that visualizes the site-specific sound character and seasonal changing of light in the city was developed.
