Competitive analysis and market research using House of Quality methodology to identify design requirements and tradeoffs.
"All-in-one" approach, where reading the user's chord input and processing the audio would be completed on the same microcontroller held by the performer.
This design consists of an entirely software-based approach. It would have the cheapest reproduction cost, but offered the least mobility and freedom to the performer.
This concept employed the ability for performers to control the chords played from the microphone itself, not limiting their range of use to being near a computer to add effects to their vocals.
This concept introduced the idea of a "frequency modulation box" (FMB), eliminating the risks associated with bringing a computer to a performance. For this idea, the process of audio manipulation would be completed using only standalone devices.
My team and I valued the benefits of the "all-in-one" approach over any of the other options, and this sketch was my primary depiction of this device. It would wrap around nearly all stage microphones using a Velcro strap and a hinge attaching the microcontrollers to the buttons for different shapes, sizes, and angles of microphone handles.
After evaluating our budget and time constraints, the team decided to utilize a disjointed approach. This allows the musician to maintain full mobility around a stage without interacting directly with a computer, while still providing room in the controller for a larger battery, circuit board, and ergonomic flexibility.
Complete signal flow chart showing each step of audio processing from input to harmonized output.
As can be seen in the final sketch above, we had to create the FMB to alter the audio to a desired chord structure, as well as a remote to chose said structure. We opted to use a Raspberry Pi 3B+ with a high fidelity hat as the FMB.
I created a custom PCB for an ESP32 microcontroller in the remote to be able to communicate with the FMB via Bluetooth. The PCB connected the microcontroller to four buttons representing 16 combinations, a power switch, a multi-functional LED, and an internal, rechargeable battery.
Completed vocal harmonizer system showing final controller design and FMB integration.
An overlay displays the idealized output that should be generated by the instrument when a user selects each chord given an input frequency of 500 Hz.
A spectrogram I designed of the actual results of each chord type produced from a recorded 500 Hz sine wave.
The idealized outputs and measured frequencies overlain, where one can see direct alignment.