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How to Soundproof an Air Vent: Reduce HVAC Noise!

Whether you’re looking to soundproof your bedroom or eliminate distracting sounds from your home office, you’re going to find that there are numerous sources of noise.

Even if you’ve soundproofed your ceiling, walls, and floor, some unwanted noise may still be seeping through. What’s the source? – It could be your air vents.

Though they're often overlooked, air vents are a notorious source of noise. Sounds from adjacent rooms, wind, and other irritating noises can seep through.

While you could install covers over the vents, it isn’t the best solution. Covers can restrict the flow of air from your vents, preventing them from performing their intended function. Fortunately, there are ways that you can soundproof an air vent without disrupting airflow.

The Different Types of Noise

Before we discuss air vent soundproofing methods, it’s important to discuss the different types of noise. The goal of soundproofing is, of course, to eliminate or significantly reduce unwanted noise; however, because there are different kinds of noise, you need to know which types you’re dealing with so you know which strategies to employ.

There are two main types of noise:


airborne noise transmission

Airborne nose, as the name suggests, is noise that travels through the air; voices, televisions, etc. Sound waves are transmitted through the air until they collide into a solid object, such as a wall. This collision transmits those vibrations through the object and into the space beyond it; hence why you can hear someone in the next room talking as if they’re standing next to you.


impact noise

Structure-borne noises, on the other hand, occur as a result of an impact with an object on a structural element; a pot falling onto a floor, footsteps on stairs, or a chair banging into a wall, for example.

Structure-borne noise occurs because the impact that occurs between the object and the structural element causes both sides of the structure – the floor, for instance – to vibrate, and that vibration creates sound waves.

Air vents can be a source of both airborne and structure-borne noise; therefore, a variety of soundproofing techniques may need to be employed.

How to Soundproof Air Vents

There are several strategies that you can use to soundproof an air vent. Below, we highlight a handful of strategies that can effectively reduce the amount of noise that’s traveling through your vents.

Acoustic Foam

acoustic foam material

Acoustic foam helps to minimize echoes. As soundwaves bounce through the air, the foam picks them up, preventing them from creating an echo-effect. This material isn’t intended to block out noise, but instead, it’s designed to enhance the sound quality in a room; hence why acoustic foam is commonly used in recording studios and movie theaters.

For air vents, acoustic foam can prove to be an effective way to reduce noise because these structures tend to generate a lot of echo; this is particularly true if they’re constructed of metal.

Therefore, this material can absorb the echoes that pass through the vents, thereby minimizing the amount of unwanted sound that’s traveling into the space you’re trying to soundproof.

To soundproof your air vents with the material, follow these simple steps:

  • Remove and measure the air vent covers.
  • Cut the acoustic foam so that it’s the same size as the vent covers.
  • Apply adhesive along the edges of the interior of the covers.
  • Attach the foam to the covers, ensuring that all gaps are covered.
  • Replace the covers on the air vents.

Create a Sound Maze

A sound maze is one of the most effective soundproofing techniques for an air vent. A sound maze won’t prevent air from flowing through the vent, so ventilation won’t be an issue, yet it successfully deadens unwanted sounds.

That’s because the maze creates several surfaces within the vent, and the soundwaves will need to bounce off of those surfaces in order to enter into your room. As such, the amount of noise is significantly reduced. However, while it’s effective, creating a sound maze can be a bit labor intensive.

To create a sound maze, you’ll need the following supplies:

  • Acoustic foam
  • Plywood
  • Green glue
  • Utility knife
  • Measuring tape
  • A saw; handsaw, power saw, etc.

Use the following instructions to build a sound maze in your air vent:

  • Remove the cover from the air vent.
  • Measure the interior of the vent.
  • Cut the plywood so that it will fit inside the vent, and then cut around 30% off of the end of the wood so that air can travel around it. Create a minimum of four plywood pieces of the same size.
  • Attach acoustic foam to both sides of each piece of plywood using green glue.
  • Secure the plywood piece in place by applying glue to one edge and slipping them into the air vent, leaving about an inch of space between each one. The panels should be attached to the interior of the vent in an alternating fashion, for example, the first one on the left side, the second one on the right side, the third one on the left side, and so on.
  • Apply acoustic foam to the back of the air vent, using green glue to secure it in place.
  • Replace the vent cover.

Seal the Air Vents

You can also try using a sealant to prevent the transmission of soundwaves from traveling through your air vents. We recommend using an expanding foam for this technique, as it will do a better job of filling in the gap.

Apply a generous amount of sealant to the interior of the air vent in question. Once the sealant is in place, it will expand to fill up all of the available space. Wait a few minutes to see if you need to add more; apply more if necessary. Once the sealant sets, there will be an airtight seal inside the air vent.

Next, smooth out the surface of the sealant with sandpaper and reposition the air vent cover.

Block Up Your Air Vents

Lastly, if you really want to soundproof your air vents and you don’t mind if they no longer function, you can block them.

There are several ways that you can block up your air vents to create a soundproof barrier. Some of the different options that we recommend include:

  • Hang soundproofing material over the air vents. Remove the air vent cover. Cut the material so that it’s the same size as the interior of the vent. Use an adhesive glue to secure the material to the interior of the vent. For even more soundproofing power, apply another layer of materials to the exterior of the vent.
  • Cut a piece of plywood so that it’s a little bit smaller than the back of the air vent covers. Use adhesive (we recommend green glue) to secure the plywood to the interior of the vent cover. For even more soundproofing, apply weather stripping tape around the interior edges of the air vent cover.
  • Install a cover over your air vent. Standard air vent covers are louvered; however, you can purchase solid covers that do not feature any openings and install it over the existing cover of the air vent. Since there aren’t any openings, it’s harder for soundwaves to escape. To further improve the effectiveness of this technique, apply acoustic foam to the interior of the cover using green glue to secure it in place.

Have Your HVAC Inspected

hvac inspected

The noise that’s escaping through your air vents may be due to a problem with your HVAC system. If you’re hearing a lot of banging, thumping, whirring, and other similar sounds, a faulty HVAC could be to blame.

Contact a reputable and experienced HVAC technician and have them assess your system. If there are any issues with the system, the technician will be able to diagnose the problem and make the necessary repairs. Not only will having your HVAC system repaired help to eliminate unwanted noise, but it will also improve the efficiency of the system, prolong its life expectancy, and even reduce your utility bills.


Soundproofing an air vent can be a bit of a tricky task, as various types of sounds can travel through the tubing and opening; hence why it is often regarded as one of the most difficult parts of a room to soundproof. However, the above-mentioned strategies have been found to be highly effective soundproofing strategies for an air vent.

For maximum effectiveness, you can try a combination of these strategies, or simply explore each one until you find the option that works best for you.

James Burkett
James is a self-employed writer and editor and has the privilege of working from home. However, he quickly discovered how unwanted noise can disturb both work and sleep. Over the years he's effectively soundproofed his entire work space and a number of rooms in his house. Needless to say he can work and sleep much more peacefully.
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