I2S is a popular digital interface for audio, but is not supported on many microcontrollers. Design an interface from I2S to SPI (or I2C) that uses the smallest possible processor to do the work. Build a PCB/develop software….
See file here The file links to a paper entitled “Extracting the fingering and the plucking points on a guitar string from a recording”. Either explore the process (E12 project), or implement it (E71) in real time (E90)