Microphone connection problems with a VM

Since a couple of days I can get any audio from the microphone into my VMs.

I see in dom0’s pavucontrol that there is sound coming into the microphone as the blue bar moves when I talk. qvm-device mic says the microphone is connected to the VM, but in the VM I don’t see any sound coming in from the microphone pavucontrol or any application.

I have tried with different VMs and different templates (debian-11, fedora-34, debian-sid, …) and I see the same problem. So I assume the problem is in dom0 and not in the VMs itself. Playing sound from the VM works fine and I can hear it so it looks like the pulseaudio of the VMs can talk to dom0.

It was working fine few days ago, I don’t recall doing any changes in dom0 besides doing updates. I do have enabled qubes-dom0-current-testing repo as some times there are fixes from it that help with the many problems of the Intel Tiger Lake I have. But I have tried to reboot the computer with different kernels (5.10.112, 5.16.18, 5.17.5, …) just to check is not a problem of kernel-latest but the same problem persist. I don’t see any clear errors in dmesg neither in dom0 or the VMs.

Any idea where can I look for the source of the problem? What can it be producing it?

Check in pavucontrol in dom0 if applications (VMs really) are connected to the microphone for recording and not to “monitor of …” virtual device.

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This is the solution. It looks like all VMs in Recording tab of pavucontrol were marked as “Monitor of …”, when I change that the microphone started working.

I have no idea how I end up with this configuration, I don’t think I ever touch the Recording tab or any similar with pulsectl. Anyway I’m happy to have found it, now I know how to fix it if ti happens again.

@marmarek thank you for the solution.