Difference between PDM microphones and I2S: Why does PDM require a decimation filter?
A PDM microphone is a digital microphone that expresses audio signals as a density of pulses. The converted signal consists of “high-density ones and zeros” and includes high-frequency components that exceed the human audible range (20 Hz to 20 kHz). On the other hand, I2S microphones transmit voice data in PCM format