Preventing Sound From Traveling Through Heating Ducts

stauffek asks,

We have a ranch house with forced air heating and cooling. The master bedroom is across the hall from the nursery, and the ductwork runs under the floor between the rooms. With both doors closed, we can hear the baby in his room through the vents. Is there a way to prevent the sound transmistion short of covering up the ducts with blankets? Covering the ducts will make the vents ineffective for heating/cooling.

Our Answer

Well that's one way to save on a baby monitor!

This is a tricky situation. In theory, the best approach is to use an insulated heating duct. Insulated heating ducts are lined with fiberglass and can reduce some, but not all, of the sound transmission.
To accomplish this, though, the entire duct has to be removed and replaced – not an easy or inexpensive project. You might be better off thinking toward a future where your baby won’t be crying as much. Installing insulated heating ducts is a major undertaking for a short-term problem.

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