Tech Note 076 - ESP8266/ESP32 Audio Spectrum Analyser using FFT

In this project I use the Fast Fourier Transform algorithm to convert audio (in the time domain) back to its component frequency parts and then display the results as bands of amplitude and frequency on an OLED either 0.96" or 1.3".
Choose the display you have by commenting out the library not required (Sh1106 for the 1.3" OLED and SSD1306 for the 0.96").

Most ESP8266 development boards have a voltage divider on the audio input and may require a larger audio drive, by contrast most ESP32 development boards have no ADC input protection. For either board a microphone pre-amplifier is useful although direct audio connection can be used if required, but careful attention is required on the maximum drive and it should be de-coupled with a capacitor of say 10uF or greater. The ESP32 does not generally have a voltage divider and so needs less audio input, say 100mV, some experimentation is required with your audio source.
Source code: https://github.com/G6EJD/ESP32-8266-Audio-Spectrum-Display
Microphone: https://www.aliexpress.com/store/product/1pc-Sensitive-Sound-Microphone-Sensor-Detection-Module-For-Arduino-AVR-PIC/612195_32299102358.html?spm=2114.12010615.0.0.311b93a8dgFGue

Видео Tech Note 076 - ESP8266/ESP32 Audio Spectrum Analyser using FFT канала G6EJD - David