“Mischief” is a series of toy instruments created as part of research for the “sound-playground.” ‘Sound-Playground’ is the playground, that i am going to make one day, where the children’s play generates the sound.

Last summer, while walking through a park in Essen, Germany, I witnessed a memorable scene. On the park’s pavement, children had drawn colorful pictures with chalk, and kids from different countries and language backgrounds were playing hopscotch together. Watching them, I realized that play is a powerful universal language that breaks down barriers.

However, in a traditional playground, each ride exists independently without interacting with the others. But what if sound could connect them? Imagine if a child’s position on a slide determined a note in a melody, or if the carousel’s rotation acted as a rhythmic instrument. In this way, sound becomes a bridge, turning isolated rides into a collaborative musical experience. Through this Sound-Playground, I want children to discover the joy of creating something together.

For this project, i hacked four existing toys, and designed one instrument. The toy works as a sequencer—when blocks are placed on its panel, it starts playing, and the weight of the blocks determines the notes. The Hammer bank functions as both a sample player and a looper. The rocking horse adds a reverb effect, the RC car generates synthesizer sounds, and the airplane creates bass sounds.

The wooden block play panel was designed and built to function as a sequencer. Wooden blocks from existing toys were used. A Force Sensing Resistor was employed to measure pressure, and a shift register (CD4051BE) was utilized to reduce the number of pins needed for the microcontroller.

Hammer Bank has been modified to operate by installing a tact switch under the wooden pillar.

The RC car analyzed the signals from the controller’s IC chip and sent them through a comparator when the buttons were triggered, then transmitted them to the microcontroller for use.

The rocking horse and airplane toy used a gyroscope sensor (MPU 6050) and transmitted the data to the main microcontroller (Master ESP32) via Bluetooth from the slave ESP32.

### Kids’ Reaction

– The most popular toy was the Hammer Bank. Its simple operation and the sounds it produced, which resembled children’s laughter and counting, made it a favorite among kids, and they played with it the most.

– The RC car had too much stimulation from movement, and the loud noises it made distracted the children when they tried to control it. Additionally, the controller was too large for their hands, making it difficult to operate comfortably.

– The base sound of the airplane often elicited reactions of unfamiliarity and fear from the children. One child even mentioned that they thought this airplane could be flown wirelessly like a car.

– The rocking horse can be held stationary by adults leaning their body weight to one side, thus stabilizing its tilt. However, children find it difficult to do this due to their lighter weight. As a result, the reverb effect was not as pronounced as when I demonstrated it.

– The responses to the sequencer varied among the children. Some chose not to play with the blocks on the small panel, while others focused on the sounds and stacked the blocks. Some grouped the wooden blocks by color or created different shapes.

## Software

To implement the instrument, I used ESP32, Arduino IDE, Ableton Live, and Max for Live.

Link for MCU(Arduino IDE) Code, Max Device

## Hardware

## Areas for Improvement

– I couldn’t consider that children’s reactions vary greatly by age group. In the future, I will take the target age group of the children into account more when creating instruments.

– Next time, I will create an instrument that can operate as a standalone device without the help of a computer. While connecting to a computer offers flexibility in using the instrument, it may not be practical when actually creating an outdoor play area.

– I aim to create more modular synthesizer-like instruments. Currently, the toys, except for the rocking horse, play pre-defined sounds. Next time, I will develop a toy that allows two or more toys to control a single sound simultaneously, resulting in more diverse and unpredictable sounds.

– Instead of hacking existing toys, I will design and create original toy-instruments.

– Study German! I cannot communicate with the children in English.