Thanks Peter,
Actually no the tiny holes are not blocked and the imac is open with the screen lying on my table
When i opened my mac to install a new Blade SSD i had to disconnect the microphone cable.
Then i thought it was broken because i reconnected after the surgery and no sound
I ordered a new one and no sound
Did a PRAM reset and still no microphone sound
My mistake is that i did not see the tiny latch when i disconnected that microphone in the first place (it is super tiny and fragile)
I have no clue what to do, it it an iMac 27 2019 and i really enjoyed using that imtegrated microphone for facetime or videoconference