Try it out... hold the phone in your hand and start playing some music or a video. Then just set the phone on the table. If you get up close to the phone you can clearly hear it switch from the back speaker to the front. I knew the Moto X was using the accelerometer for the active display, but I hadn't realized that it does the same with the speaker.
Is this unique to the Moto X or do other Android phones do this as well? I've never noticed it and have certainly never heard it talked about before. Am I the only one who missed this?
update: thanks to 's comments below, I'm now not entirely sure if this is really happening or just my ears playing tricks on me.