Share your experience!
Does your phone has a protective case, film and/or glass that might be blocking the mic?
have you exposed your phone to water and/or steam?
Hi @Genchan,
Welcome to the community.
It may sound silly but, how are you holding your phone? The Microphone is on the bottom, it's just a small hole. If you are covering that with your finger, you will get the issue you are facing. Also make sure there's no lint or debris stuck in that hole.
Can you try to check on xperia diagnostics
Settings, about phone, diagnostics
If you recently updated you can try to perform software repair using xperia companion