ive been having issues recently on most asus models particularly on the microphone, just for a good to know basis i am a mobile technician with 19 years going 20 years already this year, any way let's have your problems on your mic fixed, it started on my own mobile which i personaly use asus Z00AD, suddenly my mic did not work then after rebooting when you call the other party hears a load static noise with my silent voice, the receiver even made fun of it and said it was like the sadako japanese horror movie, well i troubleshot my phone replace the 2 board at the bottom where the mic is located, still did not worked.. tried replacing again for at least 5 times with different suppliers it was a complete failure. i was more eager to fix the issue, stopped finding solution after 3 days. the i came back checking the schematic diagram i found out that the bottom mic is only a secondary for persons that has lesser voice sound that is the same reason they built two instead of one. the main mic is at left top beside the flash for the camera. so here's what i did, i removed the mic below on the second board where the charging pin is located using my hardware tool we called hot air, i just thought of it as logical. the to my suprise it worked my mic is fixed i can be heard again by the other party. problem solved. after a few days a recieved a job order to fix the same problem on a different model asus X013D do to my personal experience i also fixed it using the same method, i used this method time and time again infact even now after i fixed the asus phone i just shared this info.
i know you guys will ask why this happened?
answer is, engineers often create an idea that will make the user at ease of use but the ic that is created is just recently invented, this also means this companies is selling us items that just came out recently with no credible testing, but due to demand they sell it, for product competition.
funding is expensive and they need to get it back as soon as possible....logical speaking right..
how technology work's now is different from before, advance tech at the earliest days was more precise with no compromise, but now get the demand then the technology will follow. result is staggering factory defects and more warranty services, it is good for us service guys, but hassle for consumers.
hope i helped you guys on this issue any question feel free to respond back, i am happy to help and answer