Comment 1 for bug 1597804

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.