wallSound / Final paper text


The term “wall of sound” was first used to describe the mystical space of music perceived by the audience in the redesigned theater by Richard Wagner, which placed the orchestra for the first time out of sight. The term became popular around the mid 1950’s to describe the sound of jazz orchestras, and gained popularity in the 60’s when music producer Phil Spector used the name for his new technique to record dense layered reverberant sound for AM radio, using many guitarists playing the same lines together in an echo chamber. The term was later used in rock music to describe the effect of two distorted rhythm guitars playing together giving an amorphous quality of sound.

The “wallSound” is a modular sound interface that uses body conductivity and requires body contact and movement to manipulate sounds. It discusses the human-wall relationship, by creating interactions that depend on both. In different scenarios, the wall and the human play different roles in support of each other.

The vertical plane structure of the interface requires the body to move in a new self-aware way, and break out of the limited bank of everyday movements required from the daily activities of walking, sitting, climbing stairs, etc.

A wall is not built to interact with the body. The project deals with the wall’s limited affordances, and the low expectations that come with interacting with it. Leveraging the wall’s flat vertical surface turns it into a surprising and playful physical experience. This encourages the body to reconsider its physical environment, and creates potential for a new dialogue between the two.


wallSound refers to various precedents in different fields: Sound installations, touch interfaces, skin, body, movement, music theories and performance art.

Audio Grove by Christian Möller is an interactive light and sound installation made in 1997 at the Spiral/Wacoal Art Center, Tokyo. At the base of the installation, a circular 12 m diameter wooden platform, on which sit 56 5.5 meter tall vertical steel poles, creates a ‘steel forest’. Each of the steel poles is connected to a touch-sensitive sensor system. The installation is the interface through which light and sound can be physically experienced and controlled. Touching a pole evokes a specified sound that echoes and melts with the next touched pole sound. Touching a series of poles will produce an echoing harmonic accord.

Skintimacy is a skin-based musical interface that explores interpersonal boundaries through collaborative musical performance. Made by Design Research Lab at the Deutsche Telekom Laboratories and Technical University Berlin, Skintimacy deals with the question: How can an intimate interaction between two bodies be experienced through, or translated to, sound? It is an evocative tool for interpersonal interaction through touch and an alternative experimental collaborative musical instrument that creates bodily-close haptic and emotional experience.

The Artist Kate Hartman built a wearable wall, a portable structure worn as a backpack that is used in a variety of situations. Dressing up with this wall involves breaking out of ones physical form and dimensions.

The project is also inspired by experiments in music during the 20th century, made by composers like the Futurist Luigi Russolo and John Cage that shook the foundations of the aesthetics of music as perceived back then. Their research into untraditional sounds, as apposed to tunes, turned music into a fluid process, breaking the composer’s control over the performed musical piece.

Last is mentioned Gaga, a movement discipline developed by the choreograph Ohad Naharin, that raises awareness of physical weaknesses, awakens numb areas, exposes physical fixations, and works on ways to eliminate them.

All these precedents, when raised, inspired and enhanced relevant points for consideration in the process of developing wallSound.

Interaction and Prototyping

Working on wallSound's technical aspects, I began looking into different conductive materials, as well as capacitive sensors, with and without additional hardware, that will work with the human body resistance similar to a 200 kilohm resistor.

The search after the right circuit started at a hacker's theremin project. The circuit is built out of two NE555 timer chips and two photo resistors that manipulate one output speaker’s pitch and powered by a 9Volt battery. In this circuit the NE555 is being used in its astable mode, meaning as an oscillator. The chip feeds current into the capacitor until it is full, and then drains it out. The frequency of the oscillation is set by the resistors and capacitors: The resistors set how fast to fill and drain the capacitor. The size of the capacitor indicates how long it takes before it fills. This experiment failed to give a clear reading when touching two stripes simultaneously, interrupting with the playing and distorting the sounds.

The final wallSound circuit is built using CapSence Arduino library that turns the Arduino pins into capacitive sensors, which measures body resistance and read the changed output frequency. The circuit includes 1 megohm resistor between the send pin and the received pin which is the sensor pin. A wire is connected to the copper that absolute touch activates. The delay between the send pin changing and the received pin changing is determined by the resistor and body capacitance. This structure was duplicated in a way that each circuit reads one copper stripe. The Arduino communicates with Processing. Using Ess sound library, patches of mp3 are being played and paused in correspondence to the state of the circuits.

After setting up the first installation, and before beginning iterations, a set of indicators were set, upon which their success or failure will be tested: The amount of people drawn to interact with wallSound will be one measure of its success, along with their level of surprise after discovering the new affordances that this still surface now holds. The level of interest working with the body as a source of power activating and mixing sounds will also be measurable elements for the wallSound’s success as a concept and as an interface.


In the first iteration called “wallSound”, the wall becomes a playful musical interface that produces beeps and sound effects. In this version, the speakers are revealed, becoming a part of the interface design. This first iteration was made to check the assumption that people will be attracted to the copper stripes with its shiny texture and will be curious enough to touch it. The loud generic sounds gave a quick feedback, and make a fluent interaction.

In the second iteration, “a wall between us”, the wall creates an illusion of a couple fighting behind it. Touching different copper stripes will activate male or female roles in a dispute. The audio has a muffled quality, which give the illusion of forbidden eavesdropping to a private conversation and makes the viewers press themselves against the wall. The speakers were partially revealed, ruining the illusion of a true wall separating the viewer from a steamy private conversation. This iteration was made on a wall that affords sketching and some free illustrations covering the wall, disrupting the clean minimalistic design and adding unnecessary and unclear elements to the story. The interaction was clear to some and confusing for others: No instructions were presented. The curious ones managed to reveal the story through the desired interaction, but many missed knowing there must be some expected experience, and were frustrated by the impermeability of the wall.

In the third iteration “waterPole”, two stripes of copper are positioned vertically one across another on a pole. Touching both stripes simultaneously makes the viewer wrap their arms around the pole in a hug, and the wall in return hugs back with soothing sounds of running water. There were no instructions given to the viewer. Due to the fact that it is impossible to see the two stripes simultaneously and hard to discover the feedback that is being given only by touching both, this iteration did not produce affordances revealing the interaction. When given specific instructions, viewers enjoyed the interaction: the relaxing effect of the hugging act, the cold texture of the pole, the soft natural sounds, and they stayed in the pole-hugging position for a while, mostly smiling.

After revising all three iterations, conclusions about the final design have been made regarding the look, feel, interaction and content.

Final Design Proposal

“wallSound” is a modular sound interface that can be placed on different surfaces in the built environment of a public or private space. The project leverages the walls’ limited affordances for interaction, and turns them into a surprising and playful physical experience. This encourages the body to reconsider its physical environment, and creates a potential for new dialogue with common elements of the built environment that surrounds us.

wallSound uses body conductivity and requires bodily contact and movement to manipulate sounds. It consists of vertical and horizontal copper stripes distributed on a clean wall, connected to speakers. Data concerning the touched copper stripes passes to Processing through an Arduino board, activating patches of sound. The body functions as the switch, affecting an electric circuit when contacting the wall. The composition of the stripes being placed on the wall is drawn from the consideration of the target audience’s height (adults, children), wall dimensions, space acoustic and the desired body movement and combinations.

Most of the required wiring work is being camouflaged with regular ready-made objects that the eye is accustomed to when placed on walls, like wire management system boxes and wiring tracks. Hookup wires attached to the copper stripes go down to the floor, covered with white tape, giving a clue that can lead to the exposure of the structure and the apparatus driving the installation. The wires run along the floor to the far side and into a box attached to the lower part of the wall which hides the Arduino board and the electrical circuits. Above the stripes, attached to the wall, are the speakers vibrating the sound into the wall, creating the illusion there is a scene going inside or behind it.

Patches of mp3s are being played whenever one of the copper stripes are touched. In accordance to the iteration’s concept, the sounds are being played in stereo, or amplified through different speakers. The sounds tell a story, a secret, or reveal an illusion of what is behind or within the wall. Lovers fight in “a wall between us”, synthesized sounds resonate in the “wallSound” basic installation, and the sound of water pours out in “waterPole”. After these three iterations in which the wall is being used to generate experience, it seemed interesting to put the wall at the center of attention by turning it into a living vibrating independent entity for the final iteration. Touching the wall will reveal its true personality and needs.

The wallSound started with the assumption that, like crows, humans are drawn to shiny materials. Therefore, they will be attracted to the copper stripes with its brilliant texture, and will be curious enough to touch it for the first time. On a tiny piece of white tape, the words ‘touch me’ appears, daring the viewer to touch. The copper texture combined with the clues being spread through the wiring system and the teasing text, create new wall affordances that imply a process of playing and revealing the content through touch and movement. After the first touch is being made, followed by sound feedback, the interaction is fluid.

The interface is modular, keeping its inclusivity: It can be set at any space, in any hight, with content curated for audience and space, and addressed to all age groups. This allows the work to always facilitate the human-wall relationship without restriction.