Noise Transfer Between Spaces via Duct

[ME27272727]

Imagine a straight line of adjacent offices spaces with a straight run of return duct and bottom taps to grilles. Would a better solution be to side tap off of the main, causing two more 90 degree angles to mitigate noise transfer from space to space? Would there be a noticeable difference?

Thanks.

 

[dbill74]

Offsetting the RA trunk and using tee's and elbows to get to the RA grille is definitely the better solution and yes, there will be a noticeable difference in sound levels.
You can further reduce noise transmission by lining the RA duct branches or using duct-board for the branches in lieu of sheet metal.

You don't mention if this is in regard to new construction or an existing scenario. Other sounds transmission methods between offices is through the walls and through the ceiling. This can be mitigated using sound attenuating batt insulation in the walls and on the office ceilings. If this is in regards to an existing condition, adding sound batt on the ceiling will help a lot, and be cheaper than reworking the ductwork.

I have also seen white noise generators used above the ceiling to mitigate sound transmission between offices.

 

[DBronson]

ME:

We use a 90 degree side tap and then an 8' section of insulated flexible duct to connect to the supply diffuser. We use a similar detail on the return grille (for plenum returns). Works quite well.

Regards,

DB