The tunnel audio is caused by the speakers feeding back into the mike. With a ppruner last night, we tested the audio while counting as I dropped the speaker volume, and the tunnel effect fell with the speaker volume, with a headset, it was gone.
I bought a Tandy headset for $19 which works perfectly, the mike is clear and sharp.
So far, conversations from the esat coast US (South Carolina) to UK, Kuwait and Mexico have all been virtually perfect, with no delay and sound that is like a CD's audio.
And the price is just right!