MICROPHONE ISSUE
We are getting customer complaints that microphones are muffling speech and the other caller cannot hear them properly. Reviews are also appearing on Kimovil and elsewhere, so this is a reputational issue for Blackview which you need to address given the higher prices now being sought for handsets pitched at the premium market.
We see the phone has "active noise cancellation" - is this inadvertently interfering with speech into the phone? Please can engineers test some phones and advise. The BV9500 does not currently allow engineering mode to be accessed so outside tech support cannot currently assist your company in diagnosis and tweaking.
Blackberry had a similar problem with their early attempts at noise cancelling microphones:
https://forums.crackberry.com/blackberry-storm-f86/any-way-turn-off-noise-cancellation-134921/
Motorola have same issues this year:
https://forums.lenovo.com/t5/Moto-X4/Voice-quality-issue-Microphone-Issue-Active-Noise-cancellation/m-p/4081739#M3625
ADMIN EDIT:
Found the problem...it is definitely the coding for the Active Noise Cancellation system (Accessible through Phone App, three dots menu/Settings/Accessibility).
When you turn that system OFF, the problem appears to go away, but the phone does NOT save the setting when it is turned off - it reverts back to a default of Noise Reduction turned ON.
So you have to remember to turn Noise Cancellation off every time you restart the phone. Which is not a good solution.
This explains why people who turn Noise Reduction off are reporting the return of the problem later on. It comes back when you restart the phone.