Final project: Sound Kites

Get the code: Arduino + Processing

My final project for Physical Computing (with Yu Ji) is called Sound Kites. It is an installation/space consisting of sheets of fabrics and materials hanging from the ceiling to a height of about seven feet off of the ground. Attached to these sheets are strings which trigger a soundscape when pulled on.

This project evolved from a few different ideas that we had which centered around using a fan or source of air to create interesting interaction. One idea was to amplify a user's breath by syncing it with a fan. Another idea involved using a fan to float the sheets of fabric in order to produce a buoyant effect. Some of this early work can be seen in one of Yu's blog posts.

After some deliberation, we removed the fan from our project entirely. It wasn't clear what the fan was adding to the experience, and we were able to create the interaction we desired without directly using air in this way.

The circuit is very simple - there are 3 stretch sensors and 3 pull-down resistors connected to an Arduino Uno. Pulling on a string stretches the stretch sensor, causing a change in resistance which is picked up by Processing (working with Arduino through serial). Two different thresholds for the sensor values cause sound to be played either normally or with a phaser effect.

The sounds were found on open-source audio websites like the Internet Archive, Freesound (windchimes), and Behance (i/dex). I edited the three sound files to make their keys more similar, and we only used portions of the files. The sound loops continuously and only the gain setting is affected when a string is pulled, meaning that it would be possible to synchronize sounds to give the user even more complex interaction.

We used the Minim audio library to play sounds through Processing, which caused us problems with the quality of the audio playback when changing the gain. This introduces pops and clicks into the audio which definitely diminished the quality of the interaction experience. If this projects goes forward we will need to explore other options for producing sound.

The project was well received by our class. One interesting thing was that most of the users, when asked later, didn't know where the sound was coming from (computer speakers sitting on a shelf). This pointed to the fact that we had completely engaged them to the point that they didn't even think about the system's operation. This fact was a big achievement for us and will undoubtedly influence our future design decisions for this project and others to come.