Sound Garden An ambient sonic display

sound garden
An installation of my prototype on the Carnegie Mellon campus in Pittsburgh.

Garden windchimes that communicate...

...the presence of moisture in the soil. My goal with this project is to convert ordinary wind chimes into an extraordinary ambient “sonic display” that informs the listener of the state of their garden’s health in a very simple way, by giving them the ability to sense their environment and subtly communicate useful information to an observer.

The big idea...

...was to have two sets of chimes, “dry" and “wet,” hang from a ledge near each other, with only one active at a time. When the soil was below a threshold moisture level, the “dry” chimes would become active, and when the soil was above the threshold, those chimes would be muted and the “wet” chimes would become active.

Using changes in timbre...

...or the quality of the sound, these chimes can communicate the "wet" or "dry" states to the observer:

  • The “dry” chimes: I originally planned to use bamboo chimes that produce hollow, staccato notes with little resonance, but realized I could achieve very similar results by wrapping each end of the metal chime tubes I had on hand with rubber bands.
  • The “wet” chimes: I chose to use solid metal bar chimes for these because of their sparkling quality and extremely long resonance, both qualities suggestive of water.
sound garden
In CMU's Physical Computing Lab, working on setting the motion range of the servos that activate/deactivate each windchime.
sound garden

Switching between "wet" and "dry" chimes...

...is accomplished by raising and lowering the height of the “knocker” that connects to the paddle hanging in the middle - if lowered enough so the knocker is below all of the pipes, even a robust wind won't produce any sound. To achieve this mechanical action, each set of wind chimes is mounted, along with a hobby servo, to a wooden board that the chimes hang from. The string the knockers hang from comes up through a hole in the middle of the wooden base and attaches to the end of the servo's extended horn.

sound garden

Analog input from a soil moisture sensor...

...is fed to an Arduino micro-controller, which controls the movement of the two servo motors. The Arduino is programmed to monitor the value from this sensor, moving the servos only when a threshold value is crossed. One can easily imagine an array of moisture sensors placed around a garden, with the micro controller’s program monitoring the average of all of these sensors' outputs.

sound garden
Adam Savage
Explaining my design rationale to the former "Mythbusters" star as part of his tour of makerspaces across the country.

The importance of prototyping...

...was made clear to me during this project: no matter how good you think your design is, it can always be made better with imnput from someone else. However, they are only able to do this because you have a prototype to show them — seeing one person’s creative output helps channel another’s creative energy so that their ideas build off of one another, rather than compete for superiority.

In the case of this project, I was lucky enough to have Adam Savage’s creative energy build off of my own: after seeing what I had made, he put forward a suggestion that would eventually lead to a simpler design that was easier to implement.

Savage’s suggestion was to hang BOTH sets of chimes, wet and dry, from the same wooden base so that one knocker could be used to activate both sets of chimes. Moreover, this would only require one servo that raised and lowered the knocker so that it was either activating the dry chimes OR activating the wet chimes: activating one automatically deactivates the other.

On the advice of Adam Savage...

...and my peers, I constructed a second iteration of this sonic display with the wet chimes on top of the dry chimes, all hanging from one wooden board. This version was demoed successfully in front of CMU professors and classmates in the physical computing lab space at Carnegie Mellon.

diagram of chimes
Schematic diagrams of the first and second version of the Sound Garden project: the first requires twice as many wires and servos as the second, which stacks one chime on top of the other so only one actuator is needed to control the system.