What to do about ventilation duct noise???


My office at work is plagued by white noise from the building's ventilation system. The ductwork is exposed and runs along the ceiling and wall. There is a large vent just above my desk, which drones on throughout the day, all year long. Noise, both turbulant and mechanical, emanates not just from the vent, but also from the entire length of ductwork.
This is a pity, as I spend a lot of time here and thus listen to lots of music. As a matter of fact, my job is also affected by the noise. I am a psychiatrist and often have trouble being heard over the subtle roar (I have a soft voice, "soothing", in the words of my patients).

Cheap fixes, like taping cork panels over most of the vent, help a little, but they inevitably fall off after a while. Plus, it is not a terribly professional look. I have no control of the heating or cooling in the building, and would not be able to make substantial changes to the existing ductwork without being arrested or at least chastised savagely.
Any thoughts from all you audio savants?
quietcity

Showing 2 responses by rives

Are your ceilings high enough that you could install a plenum (a large air cavity) that is lined with some type of sound damping material and then have several ducts come off that plenum? It might mean putting in a dropped ceiling to hide the fix, but if you are willing to go that extent it should reduce the noise dramatically. You would probably need about 8 inches to work the duct work in (might be able to do 6 inches, but it would be tough).
Not too effective. You need to create a place for the air to go and settle so to speak. An area that is considerably (2x) larger than the area that feeds it is recommended. Even larger is preferred. Then you want ducts going out from that--the more area the better. What you are trying to do is reduce the air speed coming out of the duct while at the same time shunting the internal noise of the duct. The acoustical tiles, if I understand you correctly, will likely leak air, increase airflow and actually increase the noise. I could have misunderstood what you were trying to do, but if I understand correctly, it's not advised for reducing noise.