What is the small hole on the top of the pixel 3a? Many reviews note the pixel 3a has a headphone jack on top. Yes, I like it, too.  But I can't find anywhere that describes the other little hole, the one on the right in this picture.  What is it?
If you look at the specs for the Pixel 3a and open up the Media &amp; Audio section you'll see:


  Stereo speakers
  
  2 microphones
  
  Noise suppression


The small holes are for microphones, usually multiple ones are used to improve call quality, i.e. suppressing background noise.