Default microphones not working properly

Hello,
is anyone of you having problem with the microphones?
i am, and apparently a lot of other people are complaining on sony official forums!
my phone is brand new,never felt from any height,but still people are telling me that they having really hard times understanding what i am telling them!!
they are reporting muffled voice, that comes and goes, sometimes turning robotic or with statics background.
not to mention the ****ing second microphones, that when is enabled make impossible for the other person to understand me at all!!
in your opinion can it be a software issue of maybe something realetd to a bad sealing??from what is possible to read on the internet, is not so uncommon to find phones damaged from water