Archivi tag: research

“Polifonia liquida” – sound and light installation (video documentation and project description)


(Photo credits Kristin Warfvinge)

“Polifonia liquida” (liquid polyphony) is a new sound and light installation exhibited at Inter Arts Center for the Gallery Night of Malmö (Sweden) on the 26th of September, 2015. See this previous post for some close-up pictures.

The work involves a series of 8 independent audiovisual systems (arranged as two groups of three and five), each one composed of a sound actuator (a contact speaker capable of inducing vibration into surfaces) and a point light source that passes through a water-filled plexi plate and projects the vibration-induced shape modifications of the water surface on the wall.

This project has a strictly musical focus: the compositional process takes into account both the sound material and the visuals generated by sound. Issues are raised in terms of relationship between the sonic and the visual perception, about the choice of the frequencies in relation to the images they will create and about the delay between the sound input and the visual response.

Eight independently-controlled Mighty Dwarf 26W vibration speakers (capable of low-frequency response) are equipped with custom-made plexi plates (laser-cut at FBRKN, in Malmö, and made concave thanks to a hot-air gun). These plates host a certain amount of water, which reacts to the frequency sent to the vibration speakers. Eight point-light sources (modified IKEA Jansjö LED lamps) project the shadow of water ripples on the walls of the venue. These lamps are turned on and off at will by a timed dimmer.

The work explores the idea of visualization of sound from a strictly musical perspective. The installation is not a bare game of more or less defined Chladni patterns but wants to investigate a possible re-contextualization of compositional parameters, structures and processes in the frame of an audiovisual system that is partly physical, and for this reason depending on the physical qualities of the materials involved. The response time of water to the vibrating stimuli is a fertile constraint that influences the development of the sonic and visual material along time.

There are some crucial musical aspects that have been explored — even partially — in the making of this installation:

  • tension between monophonic and polyphonic gestures, controlling how independent each audiovisual system is from each other (not only in the rhythm parameter, but also in the frequency and amplitude domain, thus greatly influencing the visual result);
  • tension between solo and tutti, also offering different subdivisions of the 8-elements ensemble and creating a dialogue between the groups and/or the soloists;
  • time-related processes, typical of renaissance music, such as dialogue between two parts (“cori battenti”), canons and so on;
  • figures of space, letting the sound and the images travel through defined paths in the exhibition space.

Another level of presence-absence of material is given by the DMX system switching on and off the lights (DMX controller+dmmer). In this case the tension between darkness and light is a filter on the visual aspect of the work and acts in the same way than the sound-silence dichotomy. Silence is not used in the installation; instead, high-pitched sine waves have been employed, for two reasons:

  • to create a complementary (in pitch) material to the low frequencies needed to make the plates vibrate (silence would have been too “absent” and to similar to certain low sounds which are not perceived as belonging to the center of our optimal auditory space);
  • to prevent the listener’s ear from getting used (and tired) of the prolonged presence of the low part of the audible range, thus giving the listener a sort of “blank space” — actually a dark space, being the high frequencies always associated with the shutting down of the lights (since the “ensemble” was considered as a sum of three plus five audiovisual systems, it happened that only three or five of the lights were off while the others were on, so in those cases the room was not completely dark).

(Thanks to Fabriken Malmö and its crew for plexi-cutting the discs. The work was hosted and created for Inter Arts Center Malmö.)


Until the realization of the final project, many tests with synthetic waves (sines, square waves, …) have been carried out with different materials in order to visualize the shapes of the water surface. The best result was obtained with plexi plates. I recorded some test videos in which different frequencies and materials produce different results. Some of those videos are available clicking on these links:

Tools for an enlightened dictatorship: embedding sound logos into people’s body

…or: territorialization of people’s body by means of soundmarks.

A soundmark is a landmark made of sound. In the frame of acoustic ecology, it characterizes an area, but in this very case it characterizes a body/a person. See the studies of Murray Schafer about soundscape and acoustic ecology, namely the book from 1977 The Tuning of the World (ISBN 0-394-40966-3), where he defines the soundmark.

  • Context

1. Let’s imagine a dictatorship (enlightened?) where every individual is forced to have a multimedia device installed in his/her body.

2. This device is controlled by the dictatorship and receives commands or data via wireless network.

3. The dictatorship decides to apply a particular sound (a sort of soundmark) to people, based on their behaviour. For example, tax evaders would be characterized by a special sound and everybody would recognize it.
4. The sound-logo may vary, depending on the behaviour of the citizen.

  • An example at Cittadellarte, November 6th 2015, 22:00
    (Performance by Alessandro Perini)

1. The logo of Third Paradise by Michelangelo Pistoletto, founder of Cittadellarte, has been rearranged so that the two symmetric curves, enchained one to each other, would form a sound wave:

2. This sound wave is a sort of DNA which generates a particular soundscape. Not only it constitutes the timbre of the sound (microscopic level), but it aso controls amplitude envelopes, pitch and rhythm structures:(2:30 excerpt from the generative sound environment. Note the accordion-like timbre derived from the Third Paradise logo-waveshape.)

3. This sound environment is worn by the designed individual, by means of a mobile device capable of receiving sound-streams wirelessly. Cittadellarte has incorporated his sound-logo into the inhabitant. The body of the inhabitant has been territorialized by a superior entity.

(A portable Bluetooth speaker was used in the performance.)

➥ A hacker could sneak into the software or the streaming system, so that the value of the soundmark could be sabotaged or tweaked.

This (provocative) project was elaborated at a residency module (2nd-6th of November, 2015) at Fondazione Pistoletto – Cittadellarte in Biella (IT), called Creating Territorialities (part of Unidee – Territoriality, Identity, Place and Possession; mentors G. Checola and T. Gliardi).

A soundwalk with mics under your shoes to record the tactile sensation of walking


During a residency module (2nd-6th of November, 2015) at Fondazione Pistoletto – Cittadellarte in Biella (IT), called Creating Territorialities (part of Unidee – Territoriality, Identity, Place and Possession; mentors G. Checola and T. Gliardi) I proposed a way to record the tactile sensation perceived by feet while walking.

The idea is to use contact mics attached to the shoe soles in order to record the vibration phenomena happening in the soles themselves. A great deal of low frequencies are present in the recording, which actually represent the most tactile portion of the spectrum.

The following video contains a test-walk recorded in Cittadellarte on November 5th, 2015. You should use good headphones if you want to catch the tiniest sonic details (for example, the metal resonances of the staircase). Gear used: 2x AKG C411, Zoom Handy Recorder, GoPro 3+ (thanks Lorenza Ippolito). Ah, you can watch it in full HD, 50fps.

A device may then be built in order to recreate the tactile sensation: two wooden boards equipped with vibration speakers, on which the “user” can put his/her feet. In the future I may try to realize this device int he near future. For now this project remains a provocative/question-triggering proposal between art, design and geography/geophilosophy.

Tactile map

(Pictures: Vittoria Soddu)


A map of tactile relationship between foot and soil

1. A person walks paths with two contact microphones attached to the bottom of his/her shoes.

2. The resulting recording is a (sonic) representation of the tactile perception of his/her feet while walking.

3. By playing back the sound with contact transducers attached to (e. g. wooden) boards, the recorded tactile sensation is returned to another person who has his/her feet on them.



Scenario 1

You are hiking in Venezuela and you are streaming live the tactile sensation to your father in Biella, who is comfortably sitting on his sofa and enjoying a drink.
The live stream could be public and thousands more people could be actually foot-connected to your experience.

Scenario 2

Thousands of different people have mapped most part of the earth by walking everywhere in different shoes, seasons, weather conditions, speeds… Everything has been inserted into a multi-dimensional map which takes into account variables such as

  • weather (different tactile sensation with snow, rain, …);

  • physical conditions of the walker (weigth, speed, …);

  • steepness of the terrain;

and so on.

This map is a description (an analytical one) of the tactile sensation induced by the ground. Musical implications include the possibilities to see the territories as sound textures (granular/smooth, dry/resonating, pulsating/rhythmically uneven, …).




➥ Augmenting the body of impaired people in order to experience the territory in different ways, or without leaving their homes.

➥ Possible medical use as (part of) a therapy of stimulation of the body, also recalling previous experiences in nature of the patient (T. Gilardi).

“Audiotactile chair” at the Darmstadt Ferienkurse – documentation video

Documentation from the first setup at the 47° Darmstadt Ferienkurse (August 2014).

The project consists of a chair with eight vibration speakers attached. The speakers stimulate the tactile perception of the audience in eight distinct parts of their body.

Realized for “Composition beyond music” workshop (Peter Ablinger, tutor)

With support by Kulturbryggan and Musikaliska Akademien

Video footage: Christine Schorkhüber

Spectral and vibration response tests on wooden planks

These are tests made on eight wooden planks (silver fir), ca. 10 cm wide, 2 cm thick, length variable between 150 and 230 cm. They were placed on a bubble wrap.

2014-06-18 10.55.39.jpg

I sent two different signals travelling through the eight vibro speakers (Mighty Dwarfs, attached to the planks via tape). Both signals were controlled via a Max/MSP patch (something between a drum machine and a granulator) which could modulate the pitch and amplitude envelope of each grain, and the duration and tempo over time.

1. Sine wave (varying around 60 Hz) continuously travelling from channel 1 to 8.

  1. Download here the 8-channel file used for the test.
  2. Download here the stereo mixdown of the previous file used for the sonogram.
  3. Download here the stereo recording (ZOOM H4) of the wooden planks resonating.

Sonogram of the original file (stereo mixdown):

Sine - clean

Sonogram of the resonating wooden planks:

Sine - wood

As you can see, the wood resonates with a lot of harmonics and side-noises (other objects were probably resonating as well) even if we send a “pure” sine wave.

2. Sawtooth wave, two sets: one around 60 Hz, travelling from channels 1 to 4; the other slightly higher (one semitone), traveling from channel 5 to 8.

  1. Download here the 8-channel file used for the test.
  2. Download here the stereo mixdown of the previous file used for the sonogram.
  3. Download here the stereo recording (ZOOM H4) of the wooden planks resonating.

Sonogram of the original file (stereo mixdown):

Sawtooth - clean

Sonogram of the resonating wooden planks:

Sawtooth - wood

A tactile feedback glove for sensing the surroundings: prototype

On the 11th of May I participated to the Wearable Tech Hackathon at STPLN in Malmö (Sweden).

I came up with an idea of producing a prototype using Mighty Dwarfs vibro-speakers on a belt, or any other wearable gear, to feedback our body with vibrations with inputs coming from all the directions.

Since the event was very much business-oriented, much more than I expected, after building up a team we discussed and modified the idea in order to meet the requirements of usablilty, wearability and low budget. Also, we decided to use the incorporated vibro-device found on our Arduino Lilypad which was provided by the organization.


After less than 12 hours we already had our prototype – thanks to our engineer Victor – which featured an ultrasound distance sensor, driving the vibration motor, installed on a leather glove.

Viktor programming  Work in progress

The prototype proved to feel comfortable and stable, with a range of half a meter. The vibration was a pulse which became faster and faster depending on the distance between the ultrasound sensor and a physical object.

Using InviTouchWearing InviTouch

The idea behind this prototype was to develop a system for space awareness to the visually impaired people, in this case a glove which lets you sense the distance of your hands from physical objects. The final device could be a movable and adaptable one which can also fit shoes, belts, caps or other clothing/accessories. If put on your back, the device can help you detect the distance of objects/people behind you (for example in a queue at the supermarket, if you are deaf or are listening to music with your headphones).

Also, many devices can be used at the same time for a tactile-augmented reality system.

Finished prototype Finished prototype

The prototype was called “InviTouch” and an embryonal website was created by Heber Andrade.


  • Alessandro Perini: concept
  • Heber Andrade: design/coordination
  • Sveta Bogojevic: design/communication
  • Victor Boström: assembling/programming

InviTouch logo

Research mission

Tonight I’m starting this blog where I’ll post articles about my research project on tactile devices.
You can have a glimpse of the author at


THE MISSION (in short)

Contact speakers are sound devices which turn any surface into a resonant instrument. My research will focus on the possibilities given by the use of multiple contact speakers, connected with their tactile capabilities: multiple sources of vibration can stimulate our tactile perception in different parts of our body (what I call “spatialization of the tactile sensation“), for example if applied on a chair. Sound can then not only be heard, but also “touched”. Being able to separately control multiple vibration devices means also to identify spatial implications of sound movement, which opens up the path for an artistic use of the sound system.

On the other hand, making objects vibrate may lead to create even visual results…


This research project is funded by Kulturbryggan (Sweden). The activities at the Darmstadt Ferienkurse (August 2014) are also supported by Kungliga Musikaliska Akademien (Sweden).


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