This was for the final Junior Design (ECE 341-342) project. For this project we created a physical music box that detects and records dominant frequencies over time to convert recorded audio into a piano tone locked version. Includes 2 prerecorded tunes and flashy RGB lighting on the enclosure. In a nutshell, the signal processing component works as follows: An audio input is segmented into blocks. The frequency spectrum of each block is computed by taking the Fourier transform of each block using a Gaussian window function. The frequency spectrum is converted into the Harmonic Sum Spectrum (HSS) to reduce the influence of harmonic overtones on fundamental frequency detection. The 10 highest peaks in the HSS are then adjusted using parabolic peak estimation (possible because of a Gaussian window function). The frequency corresponding to the adjusted peak with the highest energy is declared the dominant fundamental frequency (F0) of this block. F0s are rounded to the nearest piano tone. If the F0 falls outside a frequency range, the block is declared to contain no F0 and silence is appended to the output. If a valid F0 is present, a sine wave with this frequency with a duration equal to the length of the block is then appended to the output. Phase persists from block to block to ensure no discontinuity. Sine wave amplitude is continuously linearly interpolated between neighboring blocks to ensure no discontinuity. The output waveform is the concatenation of each individual sine wave.