By Benjamin Norbrook
The lumaphone is a chaotic delay effect for audio processing which evolves organically according to ambient light. It’s driven by a dynamic feedback loop between an LED and light sensor. The LED output is inversely proportional to the light sensor input—the brighter it is, the dimmer the LED becomes and vice versa. Sped up, this interaction creates a dynamic system that changes in character according user inputs and ambient light levels. The system is controlled by a Teensy 4.1 microcontroller communicating with MaxMSP over a serial connection. Four potentiometers and two force-sensitive resistors provide additional control. Two potentiometers are used to tune the sensor input to ambient conditions; the other two control the rate of the feedback loop and the maximum delay length respectively. The two force-sensitive resistors provide additional dynamic control; one also controls refresh rate while the other acts as a wet/dry control for the overall effect. Depending on light conditions, directly shining a light source over the exposed light sensor or shielding it with the hand will also mute or amplify the delay effect. Together, the system creates an expressive delay sound that can vary from simple oscillations to a chaotic cloud of sound.
