The frequency of a sound, and of an acoustic wave in general, is a very important physical quantity because it generates the sensation of tone. In a tone, its wavelength depends on the speed and, therefore, on the propagation medium.
Normal sound (voice, music, noise, etc.) is a complex sound, formed by the superposition of infinite pure tones, with infinitely close frequencies. Fourier analysis (FFT, Fast Fourier Transform) determines the acoustic spectrum, which is the graphic representation of the sound pressure of each pure tone in which the sound is decomposed against its corresponding frequency.
When extracting the spectrum of a sound, it is called frequency or spectral analysis of sound. It is called fundamental frequency or first harmonic to the frequency of the sine wave whose acoustic pressure, compared to the remaining component waves, is maximum.
In short, we need to develop a solution similar to the guitar tuner. Whose purpose would be to control a drum pad, so that each fundamental tone triggers an electroacoustic sound. That's what we did, but along the way we are faced with some challenges such as latency and coupling.
You can download the project in Github following this link.