I have done tests The eardrum works well in general with the parameters for gain, volume, and configuration of microphone inputs.
But with these different settings, the “Tympan” makes noises. The output audio signals are not clean on an HP output simulation resistor.
I have a Microchip card named Starter Dspic (reference DM330011). These audio output signals are clean.
Then I made an analog card with an expander - audio compressor. It makes much less noise.
what could be done to improve the output sound quality?
Otherwise we could validate the other “line” audio outputs? For example: “LOL and ROL” located on pines 26 and 27.