Buenas a todos acá en este artículo esta una solución a mi me funciono!!
Users have reported some audio issues with the Moto G, including a buzzing earpiece, and a generally poor audio quality from the external speaker as well as the headphone jack.
Potential Solution -
If you hear a buzzing sound on the earpiece during a call, you should first test it to see whether there is an issue with the earpiece itself. To do so, you have to first make sure that USB Debugging is enabled, by going into*Settings – Developer Options – USB Debugging. Then dial**#*#2486#*#* in the dialer, and that should open up the test menu. Select the first bar, then select Audio, click on Earpiece, and choose Buzz Test. Hold the phone to your ear, and you will*hear a harmonic sound that starts on a lower frequency and goes to an higher frequency, that will repeat. If you don’t hear any distortion in this loop that is played, then there are no issues with your earpiece at all.*If you do have a faulty earpiece, the only solution is to go pick up a replacement device. If there’s nothing wrong with the device, then go into*Settings – Sound – Audio Effects, and turn it off. If that doesn’t work, in the Audio effects section, go intoSpeaker, and turn the equalizer off. That should do the trick, but if it doesn’t you may need to flash a lower firmware version. You can find out more about that process*here.If you’re facing any other issues with audio quality, go into*Audio Effects, and you can change the equalizer settings in the*Wired Stereo*and*Speaker*sections separately.