Xperia xz premium microphone intermittent fault

[Stevo123uk]

My microphone doesn't work most of the time, Occasionally it works. There seems to be no fixed pattern and when it is not working I have no idea how to fix it. I only realise it is working again when I answer a call and the caller can hear me, which is becoming less frequent.

[najodleglejszy]

@Stevo123uk

do you use a phone case that could be obscuring the microphone hole?

is there any dirt/lint accumulated in the microphone hole?

[Stevo123uk]

Hi, thanks for your reply. I do not use a case and there is no blockage. I am able to communicate when I use the loud speaker option when In a phone call if that helps. 

Thanks