Audio

FFT / FHT

The Fast Hartley Transform (FHT) is a function that converts time domain signals to the frequency domain. This is similar to an FFT, but it is designed for real data, versus complex data. The FHT uses much less processing power and memory.

Arduino FHT Library

The Arduino FHT Library

300 Hz - 3.4 kHz is the human speech bandwidth. Wideband (HD voice): 80 Hz to 14 kHz

To measure sound volume and to be able to compare different measurements one to another you need to use a module where the gain is predictable. It doesn’t mean that the gain is fixed, it just means that the gain is configurable by you and does not change automatically. In summary, avoid mic modules with no gain or auto-gain and utilize those that have adjustable gain.

ADC sampling at sampling at 38.4 kHz provides a good result up to 20 kHz.

condenser microphone Sensitivity 3.7 to 46 mV/Pa. 200 V bias.

LOOK HERE:

Very useful project link:

Arduino sound level meter and spectrum analyzer

GitHub ArduinoSoundLevelMeter

Arduino Audio Input

8 bit DAC output & a resistor ladder

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