Skip to content

How to ventilate a sealed room

It’s unfortunately common to build a soundproof room with massive walls and ceiling, only to forget about the ventilation. Air needs to travel through the vents. Sound shouldn’t.

The issue with flex duct for soundproofing

Contrary to what you may have heard, flex duct will NOT solve all ventilation-related soundproofing issues. With flex vent, people typically cut 6″ diameter holes in the newly soundproofed ceiling, exposing the original framing behind the layers of ceiling drywall. They believe that 6″ diameter hole has insulated flex duct in the joist cavities to fix most noise issues, and they have incorporated a bend or two in the flex to fix the rest.

Nothing could be further from the truth.

Flex duct does not have nearly enough absorptive material to deal with sound waves. Sound will simply blast through flex duct and keep traveling to other parts of the building. There is a great deal of false soundproofing hope associated with this method. Don’t get me wrong. Flex duct has a distinct role in sound isolated vent designs, however, the flex must be combined with more standard insulation to create a significant muffler.

Soffit mufflers, dead vents are best for soundproofing ventilation systems

Soundproof Vent Duct

Soffit mufflers – also called ventilation mufflers – will lower the noise level in the vents before it exits into the main HVAC system. These ducts fit nicely in a room’s soffit.

Yet there are times when a soffit muffler isn’t practical. In these cases, a dead vent might be more appropriate.





Dead vent system diagram
The dead vent can be installed outside of the sound room, perhaps in a closet or utility room. Between the soffit muffler and the dead vent, most ventilation isolation scenarios can be accommodated.

We have manuals available to discuss this in greater detail: Soundproofing Manuals (SIM)

Get started today.

The Soundproofing Company wants to make sure your job is done right the first time; that's why it's so important that we talk before you purchase anything. These consultations are part of our service and are offered at no cost to you.

We have the lab reports, materials, diagrams, SIMS (Soundproofing Installation Manuals) and experience and you need.


Contact Us

SINCE 1999 - The Soundproofing Company has over two decades of experience with soundproofing.


FREE CONSULTATION - Buy soundproofing products with confidence. We know what works and the myths you should avoid.


CALL ANY TIME- Full phone support throughout the construction phase of your soundproofing project.



FULLY ILLUSTRATED MANUALS with material purchase (SIM). Detailed guides to give to your contractor.


CUSTOM FREIGHT QUOTES: Don't let a shopping cart charge you too much for shipping. Our shipping department knows how to get your order shipped to you quickly at the best price.

Call Now ButtonCall us