“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

“Tactile headset”, listen with your head

This is the second work created at the residency at Park in Progress (Mons, Belgium), September 2nd-11th 2014. The other installation was “Subverted spatialization interface”, described in a previous post: check it out here.

“Tactile headset” is an installation that explores tactile perception of sound as vibration.


I built a cluster of four vibrating polystyrene spheres, hanging from the ceiling. Sound was traveling from sphere to sphere and the audience could experience it with the bones and skin of their head, as in a tactile quadraphonic headphone set. This work was a way to reference headphone listening (even binaural listening, since there were four sources), but translated into the tactile domain.


Picture by Zoé Tabourdiot


Picture by Zoé Tabourdiot

New sound installation: “Subverted spatialization interface”

Foto: Zoé Tabourdiot

During the residency at Park in Progress (Mons, Belgium), September 2nd-11th 2014, I was able to produce two new sound installation involving contact speakers.

In “Subverted spatialization interface”, one of the two new works, I used three vibrating devices under a 70×70 cm wooden board. The devices were shaking the board at 30 and 60 Hz.

The piece was shown during the European night of young creation (Sept. 11th) and the documentation video was exhibited 14th-27th September (Site des anciens abattoirs, Mons).

“Subverted spatialization interface” is an ironic installation which presents a real-world version of the software interface used by electroacoustic musician to spatialize sound, often represented on computer screens as a circle that the musician can move within a square. In this installation, the spatialized vibration under a square wooden board causes a little ball to stroll around. The dimensions of visual input and audio output are then subverted: imperceptibly spatialized sound is the cause which produces visual, concrete results.

Realized at the Park in Progress sound art residency 2014 in Mons (Belgium).

Transcultures / Pépinières européennes pour jeunes artistes / Citysonic

Foto: Zoé Tabourdiot

Foto: Zoé Tabourdiot

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

Guidelines: Darmstadt Summer Courses 2014, workshop on tactile sound

Note: These guidelines refer to the tactile sound workshop that will be held in Darmstadt during the 2014 Summer Courses (August 2nd-16th). This article may be updated now and then, so come back from time to time. The call is available at the IMD website. Deadline for sending the material: July 15th, 2014.
Update June 17th, 2014: New blog post “Spectral and vibration response tests on wooden planks


The project consists of a chair with eight vibration speakers attached. The contact speaker model is Mighty Dwarf 26W.


These speakers will stimulate the tactile perception of the audience in eight distinct parts of their body. The chair will be presented as an installation, and people will be able to sit on it one at a time. The music will be experienced mainly through the body; however, the full range of the spectrum is audible. Two vibration areas will be on the back, two under the seat, two on the arm rests, two under the feet. The eight speakers are therefore coupled in four left/right pairs. These renderings hereunder provide an overview of how the final construction may look like (I used a Google Sketchup model, the actual chair will be different). You can see the placement of the eight speakers, but the cables are not visible. Each speaker has an input cable coming from a dedicated (mono) amplifier.





The 8-channel wav or aiff files will be prepared according to this channel scheme:

  1. Back, L
  2. Back, R
  3. Armrest, L
  4. Armrest, R
  5. Buttocks, L
  6. Buttocks, R
  7. Feet, L
  8. Feet, R

It must be a single file, containing the 8-track package.


The whole audible spectrum is covered, however the frequency response is not flat at all. A test has been made on a wooden chair. I used a 10-minutes sine wave sweep from 0 to 6000 Hz.

These test is only meant as an orientation, as it would differ according to the different chairs used and the different placement of the contact speaker.

In this video you see the Dwarf speaker attached to the seat of the chair. This video was made to let you hear how the sine wave sounds on the chair. You can see the frequency in real-time on the computer display. SR: 192000 Hz, Edirol FA-66 Mic: DPA 4006-TL at 50 cm from the chair (click here for the mic’s diagrams).

Here you see how the mic was placed:

An analysis via Audiosculpt shows the following spectrogram (general and zoomed views).


The perception of the vibrations on the body has been tested on the same chair, with the same sine wave sweep (see previous paragraph).
These values are only meant as an orientation, as they will differ according to the different chairs used and the different placement of the contact speaker.

  • from 7 Hz, the vibration starts to be perceived (p) ;
  • 16-35 Hz: more consistent perception (mf) ;
  • 35-67 Hz: dramatic increase (to f);
  • 57-65 Hz: peak (ff);
  • 65-110 Hz: decrease (to mf);
  • 110-130 Hz: slight increase, peak at 13 Hz (mf);
  • from 130 Hz: slow decadence, with a small peak at 260 Hz and disappearing after 300 Hz (p – pp).


The idea is to use the spatialization of the tactile sensation on the body of the listener.

Different categories of spatial characterization can be analyzed in the pieces:

  • Solo Vs. Tutti
  • Left Vs. Right
  • Up Vs. Down

But note that crossfading the signal between two or more points would not probably give the sense of a smooth transition in the space. Therefore, think in “blocks” or voices.

Other explorable territories are:

  • Pulsating sound becoming continuous and back; rhythm/pulsation Vs. continuous sound;
  • Polyrhythm Vs. Isorhythm;
  • Dynamics, Crescendo and Diminuendo;
  • Relationship between vibrating gestures (7-250 Hz) and audible-only gestures (over 400 Hz);
  • Music for deaf people.
  • Tactile sensations: granular, smooth, sharp…

Sound sources can include synthetic sounds and concrete material, but keep in mind that the frequency response of the chair will filter the sound and make some frequencies resonate way more than others.


The participants at the workshop in Darmstadt will have the chance to get acquainted with the construction, discuss, experiment, and tweak their pieces in order to adapt them to the actual tactile sound chair. The pieces can also be expanded in length if needed. The final compositions will be presented in a playlist before or after key-concerts and events in the frame of the Darmstadt Summer Courses 2014.

Please bring your laptop with your favourite multitrack audio editing software.


You can address specific questions to: touchmysound[at]alessandroperini.com

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 www.alessandroperini.com


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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