Bad phone sound quality with Meizu Pro 5

After careful checking, I found out that the echoes only occur when using the phone in the normal mode, i.e., no headphones connected and the audio speaker switched off. It seems like there is a feedback loop in the hardware somewhere. If you turn on the audio speaker, the echoes vanish (it seems that the speakers are driven by another audio amplifier than the one of the phone speakers, I read somewhere that the Meizu Pro 5 has two audio circuits). The same happens when you connect a headphone via the headphone jack. I guess that the echoes would also vanish if a bluetooth headset is connected but I cannot check this because of the BT bug.

Now, I think that I know the problem (thanks to Dalton Durst): the top mic which is there for noise cancellation, is on and records the audio from the top speaker which hears the person at the end of the line as an annoying echo. (People start to hating me for that!)

Woukd it be possible to turn off the top mic?

It would be very appreciated if this bug together with the bluetooth bug is considered in the next OTA update if there is any ... :-/