Same problem - How I resolved it
Sorry for bumping a kind of old post, but anyway...
I had the same problem with the mic not working on my note 3 since the day i bought it, I bought my Note 3 used off Craigslist, and when I got home I realized that the microphone didn't work on calls, but worked just fine on speaker phone. I was somewhat annoyed by this, thinking I got screwed on craigslist again. But instead of throwing a fit about it, I just ordered another charging port / microphone thinking that would solve the problem. I installed it when it arrived, all excited like, only to find out that this didnt fix the problem. I read several posts on this forum and others, many offering what seemed to be viable solutions, disabling noise reduction, cleaning out the mic hole with a pin and so on, none of these worked, the problem still continued.
So tonight I set out on a mission to find the cause of the problem and i did just that... I started by taking my phone apart so that I could clean the mic hole from the inside as well as cleaning the little screen / filter on the inside of the mic hole and stuff like that, I was working in an area that had awkward lighting (my patio), and so I was having to move the phone in different ways so I could see down around the microphone, while doing that I noticed the light glimmering around the area of the mic hole, on the inside, I looked a little closer and I could see that there was definitely something there. I picked at it with my tweezers and what came up, a piece of clear plastic that resembled the plastic you find wrapped around the edges of new electronics, it was about 1/8in wide and 1" long, and it was covering the mic hole.
After removing the plastic, I reassembled my phone and tested it, now the mic works great. it seems that samsung put this thin plastic there to keep things out of the microphone, and it works well, it keeps everything out of the microphone, including the sound of your voice..
Now my Note 3 is what it was supposed to be from the day I bought it, an awesome phone. Prior to tonight its been a regretful purchase and disappointing upgrade to my Note 2, which I had regretted getting rid of, until now...
