Problem with microphone or something else ?

A

AC Question

I bought the phone exactly Doogee DG700, generally proved to be a very cool everything works nicely, but after the first talk test - appear problem. When i call or someone call to me the voice from me is very poor, sometimes person on the other side hear echoes, sometime distorted voice. They say that I was sitting in a bottle, or talking through a thick rag.
What I did :
- I change microphone on 255 in-service menu in engineering mode. Unfortunately, that wont help.
- I read that a lot of people have such a problem, but the problem disappears when you turn off the "Noise Reduction" or "strengthen the voice " I couldnt find this option. Android 5.0 in the event.
- Recorded video, voice recorder - it seems to me quietly, but without distortion, and you can hear everything well, so microphone is working and is not badly soldered or placed.

What do you think ? I thought to downgrade 4.4 system?
It seems to me that the system is trying something to clear the voice but to much.


Do you have any ideas?
I'm already powerless :(