What is in the shell - Ocean

What is in the shell

This project comprises of two seashells that one can listen to. The first seashell synthesizes underwater ocean ambient sounds depending on the shell’s tilt. The second seashell streams several distorted radio channels.

This description concerns the ocean shell.

This project was done with great help from Matti Niinimäki. Check for more info on the exhibition page!

Inspiration

It was my mum who told me that the seashells remember the ocean. With a childish response, I listened and listened to the hum of the moving water, crushing of the waves enclosed in this cavity. I wonder, what the shell would remember now, with the expansion of human environment, dooming overpopulation.

Producing the sound

The shell acts as a resonator for the buzzing transducer (audio exciter) placed on the inside of the shell. Based on the data read from the accelerometer, a sound is synthesised using the Teensy Audio library. I am using the design tool available online to structure the audio system. Here is a useful tutorial on the sound synthesis.

The sound of the ocean is the pink noise (pink1), filtered with a low pass filter (filter1) and reverbed (freeverb3).

The underwater sound of the crushing waves is the pink noise (pink2) filtered (filter2) with the cut-off frequency controlled by a sawtooth low-frequency oscillator (LFO) (waveform1), reverbed (freeverb4).

The bubble sound is a sine wave (waveformMod1) with frequency modulation controlled by a custom wave (waveshape1). The frequency of the custom wave is in turn modulated by a sawtooth LFO (waveformMod2). The output is then put through the delay effect (filter3, mixer1, delay1).

The three components are then mixed (mixer3). The three dimensions of the tilt of the shell are mapped to control different parameters of the sound effects.

x: room size of the ocean reverb, cut-off frequency of the ocean filter

y: frequency of the wave LFO, cut-off frequency and resonance of the wave filter

z: frequency of the bubble sine wave, frequency and amplitude of the bubble LFO

Hardware

All the electronic parts are placed inside the cavity of the shell. Small battery provides the wireless power to the circuit. The charging is done using the LiPo USB charger. The battery lasts for around 3-4 hours. The audio amplifier was needed to strengthen the signal from the board to the transducer. The audio exciter is placed on the surface of the shell and its buzzing resonates with the shell producing the sound. The accelerometer measures the tilt of the shell along all the three axes.