I'm in CT and having same problem with my phone. Need to figure this out just got it last week. If this is a glitch in the Turbo 2 will have to get an LG.
As suggested above, this could be due to a problem with noise cancellation. There are several microphones on the Turbo 2 besides where you think, and if (say) you have a case that covers any of the other microphones, it can cause this issue.
Another issue could be Advanced Calling (VoLTE) if you have that feature turned on. On two different phones, I've had issues where people could not hear me when I had that turned on, so now I only use it when I am traveling on highways, where I can be more certain of good LTE coverage and when I want to use data for driving directions using Google Maps. (Advanced Calling allows simultaneous voice and data over LTE. Otherwise, when you are on a call, you can only access data within apps when you have WiFi.)