This is a microphone module with an inbuilt preamplifier. The onboard mic will detect the sound, the MAX9814 will amplify it using smart automatic gain settings and provide an analog output signal on the output pin. This output pin can be directly connected to the ADC pin on your Arduino, ESP32, or any other microcontroller.

This latest microphone amplifier module is a step above the rest, with built-in automatic gain control. Perfect for use in environments where the noise level cannot be predicted. The AGC in the amplifier means that nearby ‘loud’ sounds will be quieted so they don’t overwhelm & ‘clip’ the amplifier, and even quiet, far-away sounds will be amplified. This amplifier is great for when you want to record or detect audio in a setting where levels change and you don’t want to have to tweak the amplifier gain all the time.

The chip at the heart of this amp is the MAX9814 and has a few options you can configure with the breakout. The default ‘max gain’ is 60dB, but can be set to 40dB or 50dB by jumpering the Gain pin to VCC or ground. You can also change the Attack/Release ratio, from the default 1:4000 to 1:2000 or 1:500. The output from the amp is about 2Vpp max on a 1.25V DC bias, so it can be easily used with any Analog/Digital converter that is up to 3.3V input. If you want to pipe it into a Line Input, just use a 1-100uF blocking capacitor in series (100uF sounds best).

Specifications:

• 3 kinds of gain settings (40dB, 50dB, 60dB)
• Supply Voltage: 2.7v – 5.5v @ 3mA current
• Output: 2Vpp on 1.25V bias
• Frequency Response: 20Hz – 20 KHz
• Low Input-Referred Noise Density of 30nV
• Low THD: 0.04% (typical)
• Automatic Gain Control (AGC)
• programmable action time
• programmable action and release time ratio
• Low-power shutdown mode
• Built-in 2 Volt low noise microphone bias
• Size: 26 x 14 x 11mm