Introduction: Urban Thump

About: Entrepreneur, Contributor, Thinker, Maker.
Urban Thump

Who doesn’t love to tap, rap, plunk, and thump on things? Creating rhythmic music with our hands, feet and found objects has special meaning for humans! Created for San Francisco’s Market Street Prototyping Festival (MSPF), the Urban Thump installation was designed to strengthen the connection between people and the community they share, by encouraging group dynamics.

Step 1: Defining the Concept

Furthering research on last year’s MSPF project, (The sound of Emotion), our team continues exploring the theory that music creates a universal language of attraction.

Researchers Chris Loersch and Nathan Arbuckle recently published a paper in the Journal of Personality and Social Psychology that explores music as an evolved group process. Their combined findings provide evidence that music may have evolved to serve the intense social needs of our species. This suggests that the powerful psychological pull of music in modern life may derive from its innate ability to connect us to others.

Step 2: Design: Inviting = Attraction?

Setting aside the complications of the electronics, our hope was to design a work that would feel polished, yet inviting, significant in scale, yet personal, and unusual at first glance, yet highly approachable.

We wanted people to step up to it and touch, as only the most subtle of vibration was required to produce preprogrammed sounds. A combination of different touches, raps, knocks, snaps, thumps, or “gestures,” could produce a uniquely different sounds, creating the possibility for a musical composition, comprised of individualized rhythms.

In the early stages, the team created a dozen design iterations, considering sculptural values, attractiveness, ability to blend into the surrounding Market Street location and very importantly, physical stability in an environment that could become quite windy and wet. As the shape and structural ideals became more defined, structural materials such as wood, metal and plastic were considered.

Brass and copper became a strong favorite for their visual properties and reflectiveness, although the challenges of working with those materials were obviously formidable. Upon further investigation, brass was ruled out, because 4’ x 8’ sheet stock was not available. That left copper as the target material for construction. Rough mockups were created to get a sense of the desired shapes and a decision was made to produce two complete walls for the event.

Step 3: Musical Technology

A UK company named Mogees, was identified as the supplier of technology to trigger the music. Mogees came to market through a Kickstarter campaign, utilizing proprietary software that is coupled with a transducer microphone. The product is capable of picking up and identifying different vibrations that may be assigned to any sound, either from a library of sounds or triggered through a midi interface.

Mogees’ typical configuration utilizes a single microphone to pick up the vibrations of any object it is attached to. Our goal was to have as many as nine areas on the Urban Thump installation to create different styles of complimentary sounds. This would be accomplished by placing multiple transducer microphones in different areas of the installation, thus allowing groups of people to create musical compositions together. It appeared the most significant challenge was to isolate the vibration to a specific area, since our structural design was to be created by using a continuous sheet of copper.

The first step was to test multiple units together, outside of the installation. This required the use of the following items:

- Eight Mogees devices

- Mac Pro Computer with Ableton Live (Midi software).

- Digital mixer and iPad to control the mixer.

- Creative Roar USB speaker.

- Appropriate cabling.

Although, their product was not typically used in this fashion, their interface to Ableton Live (a program that allows one to assemble and sync the tracks with MIDI or libraries of sound) was designed to allow multiple collection points (i.e. microphones).

Our initial testing showed the units worked well individually, but attempting to gang them up through Ableton produced intermittent issues. We were transferred to the Stateside expert to assist us, while we continued on with the fabrication.

Step 4: Fabrication Details

With the musical technology in development, we turned attention to the physical structure. Since this prototype was to live on the street for only three days, we were not overly concerned about hardening it for street abuse, but the 4’ x 8’ size of each panel would have to be secured properly, so they did not become a hazard.

After researching different construction techniques, we settled on a “sandwich” approach, that would use copper-faced flexible plywood for each side. This would also allow for space in the middle of each wall for the transducer microphones. The walls would be raised on a base that would add stability and also house the needed electronics.

The following materials were procured:

- 8 each 4’ x 8’ plywood “bendy board” flexible plywood (for the walls and base).

- 4 each 4’ x 10’ copper sheeting (roofing material) that was roughly 20 gauge.

- 8 each “80/20” aluminum T-slot, tubing as uprights to hold the wall onto the base. (

- A gallon of contact cement

- Miscellaneous hardware

The first step was to define the cutout pattern in full size, then program the cutout sizes and placement in Adobe Illustrator. The resulting .ai file was then imported into “V-carve Pro” and used as a template for cutting the pattern on four sheets of plywood using the ShopBot Alpha at the San Francisco TechShop. The plywood was 3/8” thick and was cut using ¼” double-fluted flat end mill bit.

The plywood was quite flexible when stood on end. The next step was to find a flat surface, large enough to accommodate the huge sheets of copper, so they could be positioned carefully and contact cemented to the plywood. We purchased copper sheeting that is typically used for roofing. It was thick and would scratch very easily, so each operation required a great deal of care – we didn’t want to deeply scratch the structure before it was even unveiled, since the cost for replacement of the copper alone, was over $200 per sheet!

We applied the contact cement to both surfaces (plywood and copper), then used a slip sheet method to bond the two surfaces, cementing roughly 6” at a time. We also took great care not to introduce bubbles. Once the copper was glued in place, the entire sheet was turned upside down and the center point was located for each cutout. The center point was then drilled and the copper was cut diagonally into each corner and folded over. Hammering and at times, chiseling was required to get a reasonably crisp look on the outside face. The diagonal cuts were initially done with straight sheers, but that method proved to be too slow, so a saber saw with a metal blade was used. There were 96 cutouts in total (24 cutouts per face, 2 faces per wall x 2 walls). The first wall took 12+ hours to complete. The fourth and final wall took 3-4 hours. The exposed metal on the inside face was pounded flat, taped to cover the sharp edges, then coated with flat black paint. The entire process was difficult and turned into a labor of love (or perhaps insanity;).

Step 5: Final Details

Ongoing testing with the Mogees products proved challenging, still getting results. Our tech expert worked hard to resolve the issues. Finally, through a specific series of deinstalling and reinstalling the required drivers, we discovered a stable and repeatable solution. We set up each zone/location for different sounds using one to two microphones per zone:

Wall #1: outside wall: random - interesting everyday sounds based on different gestures.

Wall #1: inside wall: drum kit - tom, snare, kick, plus various cymbals.

Wall #2: inside wall: free play – triggering very unique midi sounds.

Wall #2: outside wall: midi map – mapped to Moonlight Sonata.

A black base was created to house the electronics, utilizing the same bendable plywood, along with four extruded uprights fixed into each housing. This would allow each wall to be bent and bolted into place, using eight captured ¼-20 nuts (two per upright).

Step 6: Integration on Site

After a few days of polishing and fine tuning, it was time to load into a large box truck and assemble on site. The assembly was uneventful, although it took a bit more time than anticipated. Bending the walls into shape and attaching them to the uprights worked perfectly. Each wall proved to be stable and we decided that we could even tie then together at the top if we encountered bad weather. The transducer microphones were taped to the inside face of the walls, as assembly the was taking place. All of the final wiring was connected and the system was fired up to systematically test each area for unique sounds.

Zone one was working as expected, but none of the others were working at all! Of course, it’s easy to panic on site during final assembly, but instead we rebooted and then tested each connection. No luck. We then uninstalled and reinstalled the drives (again). No luck.

After several calls and several hours attempting to solve the problems, we decided it was time for plan B. It was obvious that the problems were located at the integration point, where the drivers were installed for Ableton Live, but there was no way to bypass that mode, unless we decoupled the microphones and ran them independently, each using their own iOS device.

In the end, we cobbled together a set of three different zones using the Mac and two iPads. It was disappointing for us, but the public still greatly enjoyed the structure and playing music, both individually and together.

Step 7: Community-Based Participation

It was very satisfying to see the public’s reaction to Urban Thump. Disparate groups of Market Street citizens engaged and often verbally collaborating to drive musical results. Kids and families were excited to create music, as well as playing peekaboo between the various cutouts. The reflective properties of the piece were uniquely beautiful -- particularly in the evening -- showing reflections from traffic lights, cars and buses.

Step 8: Conclusion

Do we consider the project to be a success? Yes! In retrospect, we should have just programmed our own software to drive the transducer microphones, but even with what we considered to be sub-standard musical output, the project achieved its intended goals of being:

  • Inclusive
  • Collaborative
  • Visually stimulating
  • Dynamic
  • Capable of creating a "destination"
  • Community friendly


Many thanks to my team for donating their expertise and time, the YBCA, SF Planning Department and sponsors for their bold initiative and tireless efforts!


Comments and questions are welcome!