It looks like there could be a problem with the microphone on some versions of the Google Pixel and Pixel XL smartphones.
A number of owners of the Pixel and Pixel XL are reporting problems with the microphones on their handsets, with some of all of the microphones on devices failing.
Google has now confirmed that it would appear to be a hardware issue and they will apparently replace the handsets under warranty.
If you have had this issue with your handset then you can get a replacement device, if you bought it from a retailer then you need to take it back to the retailer, if you bought it from Google, you need to contact their support and they will arrange a replacement device for you.
You can find out more details on how you can get your Pixel or Pixel XL replaced if you have had a microphone issue over at Google at the link below.