Why can't people hear me?

[AC Question]

I have a Samsung Galaxy 3. i bought it from someone else. everything works fine except that when i call people, i can hear them perfectly fine but they can't hear me. also, when i try to google search by voice, it doesn't work. and i tried the voice recorder thing and that didn't work either. i think it's the internal mic cuz when i listen to music everything works fine. i've looked for answers but haven't found anything. people say the factory reset doesn't work and i really don't want to go to that trouble. Help?