How The Emotion Organ works

The 2 foot pumps, keyboard, and 8 stops equipped with custom-made sensors that register how a player touches the organ with both hands and feet, and send MIDI data to various interfaces and DMX control boxes. 2 contact microphones pick up the sounds of the organ and via a digital sound interface, and feeds them into an electro acoustic sound filter. A computer running max/MSP/Jitter is installed inside the organ and manipulates the signals such that parameters (such as hue, amplitude and size) of discreet modalities (visual, aural, haptic, olfactive) and media formats (video, sound, image, aroma, text) are cross-wired. The outputs occur in the peripheral space close to the player via a foot-controlled propeller-screen, two metallic stands with antique phonograph horns housing lights and speakers, 8 airbrush guns that act as atomizers for synthetic aromas, and a stool installed with a sub-speaker. The phonograph horns are mounted on flexible goose-kneck stands. Their position can be adjusted by the player.

The two images below show a front and back view of the Emotion Organ and the elements through which sound, motion, vibration, colour and aromas are produced. The modern technology installed in its guts is visible when circumnavigating the organ.

Crossed-wired connections

The main programming concept for producing colour from sound is based on Allen Forte's system for describing chromatic sound in 20th Century atonal music (pitch class theory) and is written in the visual programming environment max/MSP/Jitter. It analyses keys as they are played and organises them into octave-independent family groups of related tonal qualities. There are 61 light sensors installed under the keyboard that send MIDI data to the computer. When the organ detects that a player has depressed at least 3 keys and entered one of 6 main, and 2 sub-groups of the Forte system it produces a corresponding colour-response in the form of a digitally projected rotating circle. The circle is projected out from the back of the organ and on to the propeller. Though the propeller stands 4 metres away, it can appear to be very close to the player. When a player switches from one group to another the hue slides across a chromatic scale in the space of 1 second to the new colour. For example, the transition from red to green will pass via orange and yellow - and so on. If a player remains in a tonal family group for a given amount of time, a corresponding aroma is released by the 8 airbrush guns with electronically controlled valves according to the chart below. When no group is registered (such as one-finger play) the result is no colour and no smell.


Technical equipment

Vintage pump organ
Custom built propeller, lamps, speakers, atomizers
Midi 9 light sensor strip
2 potentiometers
8 push-type magnet solenoids
8 distance sensors
2 contact microphones
2 customised MIDI interfaces (Interface z)
M-Audio Midisport USB 8x8 MIDI Interface
Custom-built i/o box
Eurotech Air Compressor
CLS DMX controller
LanBox-LCX DMX controller
M-Audio 410 sound interface,
KRK Rockit RP10S sub speaker
Electrix Filter Factory MK2
Infocus 120 DLP projector
Mac mini Intel core duo (1,66Ghz)

max/MSP/Jitter (4.62/1.62)

The only stored media in the organ are 8 aroma oils in the cups of the airbrush guns and 2 images - a white circle and a mask image stored in the computer. All other media are emergent and occur according to how the organ is played.

Forte Groups: colour and aroma:

The 8 organ stops have distance sensors installed behind them that act as dynamic controllers. The MIDI data derived from pulling them in and out changes the rotation direction and speed of the projected circle, as well as manipulating various visual filters and rendering modes. The foot pumps each have potentiometers installed under them. They are used to control the rotation speed of the propeller. Pump fast and the propeller spins faster. However, when the 8 stops are in play they also affect rotation speed. With one stop pulled out it is hard to gain speed, with all stops out it is easy. The affects of the propeller can be felt by the player as well as eventual spectators. It also spreads the aromas in the space. The varying speed and rotation of both the propeller and the coloured circle in combination with the various image rendering filters can produce multitudes of phenomenolgical optical illusions.

The sound picked up by the 2 contact microphones inside the organ is sent to the computer via the digital sound interface. It also passes through the electro acoustic sound filter and is sent to the sub speaker in the stool where it causes perceptible vibrations. From there it passes to 2 speakers in the medium-sized phonograph horns on each side of the player. In one mode the sound filter adjusts the frequency of the organ sound according to how many keys are depressed. As keys are released the sound frequency slides downwards, as more keys are played it slides upwards. The speed of this transition occurs according to how many stops are pulled out. The more stops in play, the longer the transition. The second mode is activated by the upper most key of the key board. In this mode a more percussive rendering of the organ sound is produced. The sound picked up by the microphones is calibrated to produce enough feedback to keep the electro acoustic sound running even when the organ is not being played.

An unmarked black key in the lowest octave of the organ activates an inversion of the way the projected imagery is rendered, creating a black hole in the centre of the image,surrounded by coloured ‘flames’. It also inverts the frequency of the electro acoustic output and generally produces low-bass frequencies.

The large lamps on each side of the player react to the sound envelope, which also affects the size of the projected image. The two small lamps react to the velocity value of depressed keys. The velocity also controls the brightness of projected colour circles.

Because sound is produced by performing three actions - pumping the foot pumps, pulling out at least 1 of 6 sound-producing stops (two of the stops do not actually produce sound on their own, but act as couplers) and depressing a key, aroma and projected imagery can be played independently of the organ's own acoustic sound. Touching keys very lightly will produce no visibly perceptible results allowing aromas to be released without a visual counterpart. The propeller can also be operated independently of the other elements. This allows for an open-ended conversation with the organ that can be expressed through both singular and multiplex outputs.

Photo credits: Annesofie Norn, Serge von Arx, Magnus Brenna-Lund