This is a minor problem but it makes me think the sound settings are not correct and gives me a chance to share my results.
I have dell e7450 (non-touch) A20 bios. Uefi boot only.
Mojave 10.14.3 & clover on msata in sata slot with adapter.(thank you Jake lo)
Windows 10 on mini m.2 NVME in WWAN slot.(when I tried clover and windows on msata I lost dell win10 activation)
note: WWAN NVME is not bootable without clover on sata or usb.
Everything seems to work perfectly except the intel wifi I plan to change.I am using usb wifi now.
Sound is good, voice memo seems ok.
My problem is Siri doesn't understand anything I say.
I went through apple trouble shooting for Siri and everything is set correctly.