This project was worked on by Lazarus Toshi and Nikita Georgiou. This project aims to dynamically cancel noise by recording sample noises and phase shifting it to physically cancel the sound.
Adafruit Wave Shield v1.1
Electret Microphone Amplifier – MAX4466 with Adjustable Gain
The MakerSpace was able to provide soldering materials as well as various capacitors in order to help alter and smooth the audio signal.
How It Works:
The Fast Fourier Transform algorithm analyzes signals and breaks them down to their frequency components. By multiplying these fourier coefficients by a complex exponential and then performing an inverse fourier transform a phase shifted signal is able to be created. This method takes some time for the Arduino to process but allows for successful phase shifts for complicated noise, making it practical for cancelling noise that is periodic. The speaker would be placed close to the ear in order to compensate for loud sounds far away.
The electret microphone amplifier outputs an analog signal which must be converted into a digital signal in order to be analyzed. Arduino’s analogRead( ) isn’t fast enough to sample higher frequencies than 9600 Hz so the wave shield helps by writing data to an SD card. The nano processes the data from the SD card and then sends it back to the wave shield to convert the digital signal back into an analog one to output to the speaker.
We were able to construct the circuitry but we still need to create an amplifier for the speaker, a 3D printed mount to make the project practically useful, and a way for the user to control the microphone input.