HTC Aria :: Defective Microphone / Sound Faint And Distant

The microphone on my Aria doesn't seem to be working properly. When in a quiet room speaking in a "normal" voice over the phone, my voice on the other line (as I have been told multiple times by different people, and as I have tested myself) sounds very faint and distant, as if I'm talking into the phone a mile away. On speakerphone, the volume doesn't change - I still sound distant regardless of how far the phone is from my mouth. Of course, if I talk louder, and I mean VERY loud, I can be heard "normally", but my voice still sounds obviously distant. I did a hard reset of the phone and have not installed any new apps, but the microphone performance has not changed.

Is this a software bug? Or is it just a defective microphone? I'm thinking of exchanging the Aria with a new one from AT&T, hopefully the policy (since I've owned the phone not even for 30 days now) won't require me to pay full price. Or does anyone know anything about their exchange policy? Because the website is not very clear on pricing (if any) on exchanges that take place before the device has been owned for 31 days or more, in which case it's free. I think, I don't know. The site is just plain confusing.