If you were to use the OpenAudio library, you'd use this example...
https://github.com/chipaudette/OpenAudio_ArduinoLibrary/blob/master/examples/LowpassFilter_FD_OA/LowpassFilter_FD_OA.ino
It does a lowpass filter in the Frequency Domain. The...
As you're using a T4, you can use floating point operations. This means that you can use one of the floating point extensions of the Audio library, like the OpenAudio or Tympan libraries. These have options for steeper filter cutoffs, including...
For Tympan, we got PDM digital mics working with the TI AIC3206 and the AIC3212. So, not your AIC. Also, we were doing I2S, not TDM. So, totally not what you asked.
If you thought it might be helpful, uou're welcome to take a look,l...