We built a home 5 years ago and the geothermal unit has always produced loud forced air noises so much that we have to turn the t.v. up when the heat is on and cover vents in kids rooms (suggestion from the furnace co that installed). Any ideas on the problem?

It could be that

The blower motor is set to a higher speed than necessary.
The duct work might be to small causing excess noise.

These are the normal causes of a noisy system air movement situation.