Acoustics 1

[bgsbny]

I am currently in the process of investigating ways to dampen the sound level in a medium pressure constant volume HVAC ventilation system. Are there any points to put an emphasis on?

 

[borjame]

Look on the internet for Helmholtz resonators, you can design very permanent, cheap resonators at very specific frequencies to damp acoustic vibrations. They're used in everything from Cathedrals to ICBMs.

 

[TheTick]

larger duct cross sections = slower air = quieter
I realize it may not always be possible.

Side note:
I used to work as an air balancer. Once, we solved a noise problem in an office at the request of the building manager. The office tenants were upset by this, as the relied on the noise to drown out outside distractions. Can't please everyone! Gravity is a harsh mistress.