Impulse Response

YouTube via pixelform. Not a synth, but some DIY correlations.
"Suspended in a 4 story stairwell, a vine of incandescent bulbs pulses and ripples with light in response to changes in ambient sounds. Loud, low rumbling from the street traffic outside causes light to shoot up through the thick rope of lights, growing brighter as the rumbling grows louder. When all is silent, the vine is dark and cold, illuminating only briefly at short but noticeable sounds: a closing door, the settling of the building, a car horn. The activities of people using the stairwell cause the lights to come alive, inviting a vocal interaction and play.

16 incandescent lights were spaces at half a meter, their power chords braided and bound together to form a gradually tapering cord of wire and lights. The rope of lights was then suspended from the 4th floor down to the top of the 1st. At the top, a nest of cables, wires, and control boxes formed an electronic spinal chord. The brain of the electronics consisted of custom digital electronics made sound reactive by a tiny microphone. As sound triggered the electronics, the lamps were turned on and off in such a way as to create the illusion of light rapidly ascending the rope, creating a brilliant column of flowing and pulsing energy.

The circuit at the heart of the installation consists of an electret condenser microphone, amplifier, comparator, two dual 4-stage shift registers, and 16 solid-state relays. The electret condenser microphone picks up ambient sounds, which are amplified and passed on to the comparator. The comparator compares two voltage levels and outputs a positive or negative voltage depending on the relationship between the voltages at its inputs. A fixed reference voltage is applied to its negative input while the signal from the amplifier is applied to the positive pin. What follows it that for every time the sound level produces a voltage above the reference, the comparator outputs a positive signal. This positive signal is then passed to the CD4027 CMOS shift registers. Linked together, the shift registers provide 16 outputs along which a signal present at the input may be clocked through. The effect is the same as a ticker tape, except that you are viewing one row of lights instead of the usual 8-10 rows that are needed to reproduce text. The signals that are passed from output to output along the shift registers are used to turn on the lamps via solid-state relays."