Samsung SCH-U620

I have the exact same problem. The guys at the store had never heard of this issue. Hate to trade it in for the same problem.
In the car, or near traffic, I cannot hear anything. I also noticed that I can hear a very slight echo of myself (not the echo you get when the phone service is being bad, but an immediate tinny echo-sound overlaying my speech).

Anyone else have this problem... and were you able to fix it? the Verizon tech suggested I use a lower volume setting, but this did not help at all.
Feel free to contact me via this forum or my profile. thanks!