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Soundproof Vent: Complete Guide for Air Vent Noise Reduction

SIlent Home Hub Soundproof Vent

Do you easily get distracted with the tiniest bit of noise? Can’t fully concentrate in your home office?

You’ve soundproofed your ceilings, walls, and floors. But what about your AIR VENTS?

A big source of distracting sounds mostly comes from air vents. Noise from other rooms, outside wind, and force of air tends to seep through these spaces.

In this guide, you will learn different methods and products you can use in soundproofing air vents.

Table of Contents

Soundproof Vents: 6 Methods You Can Do

There are TWO TYPES of air vents:

  1. Standalone / Ventilation Vents
  2. HVAC System Vents

Standalone air vents are door vents that let fresh air enter the inside of the house.

The solution?

You can soundproof the annoying sounds they make by covering them or replacing them with drywall.

On the other hand, HVAC system air vents can be soundproof-built using materials like air duct liners, soffits, and sound baffles. These HVAC vents are usually attached to an air conditioning unit which mostly causes the vent sound along the walls.

In choosing which method to use, make sure you consider the purpose of your air vent.

Will you still use it for room ventilation, or are you going to seal it completely?

The instructions listed below will tackle soundproofing techniques you can do with these two types of air vents.

1. Acoustic Foam

One of the easiest and most effective ways to soundproof is to PATCH UP your air vent with ACOUSTIC FOAM.

Acoustic foam minimizes echoes and absorbs the sound that bounces on them. It doesn’t block out sound.

Instead, the foam material PREVENTS it from bouncing off a surface since it’s a sound-absorber.

Air vents tend to generate a lot of echoes because they’re made of metal. Using an acoustic foam will lessen unwanted sound traveling through while still having the room well-ventilated.

Here is how to soundproof an air vent with acoustic foam:

  1. Remove and measure the vent cover.
  2. Cut a piece of acoustic foam, the same size as the air vent cover, so that it could fit inside the air vent.
  3. Attach foam to the interiors of the air vent with adhesive and make sure all the gaps are covered.
  4. Reattach the air vent covers.

2. Seal or Block Air Vents

If you’re not keen on the room ventilation purposes of an air vent, you can opt to remove it or seal it.

NOTE: These methods will restrict air flow and will make room ventilation impossible.

Using a Sealant

You can try using a sealant to prevent sound waves from coursing along the inside of the air vent. Better to use an EXPANDING FOAM TYPE to ensure every gap is filled.

  1. Remove the air vent cover and put sealant in the interior of the air vent.
  2. Wait for the sealant to expand and fill all the space. See if you need to add more.
  3. You now have an airtight seal inside the air vent once the sealant sets.
  4. Smooth out the sealant surface with sandpaper and return both internal and external air vent covers.

Block Air Vents

If you find the other air vent soundproofing methods not working the way you want them to, you could always just COMPLETELY block it.

Only do this if you no longer need a function for your air vent. This will completely block the air vent space from creating sound as well as ventilation.

To completely block air vents and stop the ventilation of your room, you can opt to block them with a dry wall.

  1. Open the air vent and measure its dimensions.
  2. Have a wooden plank with the same dimensions.
  3. Fill the duct with insulation material like drywall or gypsum.
  4. Once you’re done filling the vent, proceed to blend it with the wall with a wall-based adhesive.
  5. After it dries, refine it with sandpaper and paint over it to match the wall.

You can also choose to hang soundproofing products or soundproofing materials over the air vents.

  1. Remove the cover and measure it.
  2. Cut your chosen material according to the size of the interior of the vent.
  3. Use an adhesive to secure the material.
  4. Apply another layer for more soundproofing power.

You can use acoustic foam or plywood to secure the air vent opening.

3. Duct Liners, Soffits, and Sound Maze/Sound Baffle

You can do the first few methods mentioned above for standalone room vents. For vents that work on HVAC systems, you can choose to do the following.

Duct Liners

If you’re sure that there’s nothing wrong with your HVAC system, you can resort to using duct liners to reduce noise from your vents.

Installing duct liners as air vent soundproofing is cheap and easy BUT ALSO very effective.

Duct liners absorb the sound vibrating inside the vent walls as they’re made out of insulation material.

You can buy duct liners from Amazon. They usually come in 25-foot rolls, which is very much enough to cover air vent ducts.

Flexible Ducts

Flex duct reduces vent sound by providing bends in the duct, making it harder for the sound to travel when air is flowing.

These don’t entirely block sounds, but it does an excellent job of reducing them.

It prevents sounds from bouncing off on the hard metal surfaces inside the vents. These flexible ducts should only be used when necessary.

A con in using flexible ducts is that they’re prone to having small breaks, which cause the sound to still leak. This can produce a hissing sound coming from the air ducts. 

It’s ideal to use them in relatively quiet places as sounds can still enter the duct and travel.

Soffits

Another effective soundproofing material is the insulating soffit.

In soundproofing air vents, the ideal soffit is one made out of MDF with an insulation layer. Most of the time, these soffits are used in home theaters to reduce HVAC noise.

For a room that requires a higher level of soundproofing, you should ADD LAYERS OF DRY WALL with green glue in between soffits.

This is a very effective way of soundproofing air vents. To reduce more noise, adding a flexible duct will create a lot of vents that lessens the amount of sound.

Creating a Sound Maze/Sound Baffle

One of the most effective methods to soundproof an air vent is to CREATE A SOUND MAZE. It doesn’t prevent ventilation, and it’s definitely effective for noise reduction. This also works well for an above-the-door air vent.

Creating a sound maze means creating more surface for the sound waves to bounce on thus, lessening the sound entering your room.

A sound maze is also commonly known as a sound baffle. Its function is very similar to how mufflers work on cars to reduce sound coming from the engine.

Please note that while an air vent maze is effective, it requires a lot of work to make.

Here are the things you need to create a sound maze:

  • Plywood
  • Acoustic Foam
  • Green glue
  • Measuring tape
  • Utility knife (or anything else that you can use to cut the foam)
  • Saw (anything that can cut the plywood)

Here are step-by-step instructions on how to make a sound maze in your air vent:

  1. Remove the air vent cover and measure the interior of the vent.
  2. Cut the plywood according to the measurements you made so that it would fit inside.
  3. Cut an extra bit at the end of the wood for air to travel around it.
  4. You should have at least four pieces of plywood of the same size.
  5. Using green glue, cover the plywood with acoustic foam.
  6. Put the plywood in place inside the air vent with glue. Have at least an inch of space in between each piece.
  7. The pieces should be arranged alternately, one on the left and the next on the right side.
  8. Cover the back of the air vent with acoustic foam using green glue.
  9. Cover the vent. You can also choose to have your vent covers replaced if needed.

You should opt to ADD A FLEXIBLE DUCT along the crooked path created by the maze before sealing it off. This will provide a higher level of soundproofing for your soundproof air vents.

This is effective only for HVAC air vents as the ducts are much longer, therefore having the sound reduced as it travels.

This won’t be effective for a standard air vent since there is barely any room for the sound to travel.

Tip: Use Green Glue as an Adhesive

Most of the procedures above require using an adhesive to soundproof the vents. We recommend using green glue compound.

Green glue is a sound dampening compound made for soundproofing. It effectively reduces up to 90% noise. It’s not cheap, but it’s definitely effective.

NOTE: Green Glue takes at most 30 days to reach peak performance.

It’s an adhesive that also provides its own NOISE-CANCELING CAPABILITY. It has been put through multiple frequency tests to assure its noise-canceling ability.

Using this as an adhesive to secure your vents helps ABSORB MORE SOUND, thus heightening the soundproofing level of your air vent.

4. Clean Your Air Filter

If you have HVAC air vents and there’s constant noise, make sure to check the filter.

Most of the time, the air filter ends up restricting air flow when it hasn’t been cleaned for a long while.

Dirt particles end up blocking it hence, creating a surface for sound to bounce on. It causes a loud sound when it slams against the grille.

Make sure to check if your filter is clean!

5. Find a Perfect Balance with Soundproofing and Ventilation

While it is a tempting and easy solution to block and seal off your vents, having proper ventilation is still important.

Air vents control the airflow and moisture level of your home. Think of it as a way for your house to breathe.

Air vents also help get rid of unwanted musty smells caused by trapped air. Having too much moisture inside the house caused by poor airflow makes it prone to molds.

Your goal should be to SOUNDPROOF YOUR VENTS rather than fully blocking them, as air vents play an important role in your home. You can also try reducing the noise your return air vents make.

6. Upgrade HVAC System

If you’ve cleaned everything and there’s still unbearable noise, maybe it’s time to upgrade your home with a new HVAC system.

Most of the time, the reason for unnecessarily loud noises is caused by old HVAC air vents. If whirring, banging, and hissing sounds emerge, there might be leakages and gaps in the ductwork.

It gets clunky over time and can cause vibrations which are then amplified by the vent space.

Do you have a higher budget?

If so, upgrade to a more modern HVAC system.

  • Modern HVACs are built with quieter technology, giving less sound echoing from the vent. These are also energy-efficient, which can save you a lot from high utility bills!
  • Contact an experienced HVAC technician to have your vent professionally assessed. Let the technician make the necessary repairs.
  • This will not just remove unnecessary noise but will also surely improve the efficiency of the system. Doing this will also prolong its life expectancy.

It’s a pretty good investment if you ask us!

Get a Professional to Help You

In the wise words of John Maxwell, “Teamwork makes the dream work.”

If you’re not up to doing any of these by yourself, consider CONTACTING A PROFESSIONAL to solve your soundproofing problem.

A professional will be able to inspect and determine a soundproof air vent system apt for your home. It is pricier to hire someone, but it does ensure a good result.

You may have to call in a professional if the ducts’ size and length need major modifications.

Why Should You Soundproof Air Vents?

An easy solution that comes on the top of the mind is to COVER THESE VENTS.

Although when doing so, you prevent them from distributing the airflow (which is their original and intended function).

To learn more about how soundproofing a vent will help, we need to learn what kind of noise we aim to block. This is so that you would know which method will be effective for you.

Impact Noise and Airborne Noise

Two types of noises can go through your air vent, impact and airborne noise.

Impact Noise

Impact Noise Diagram

Commonly known as footfall noise, impact noise is produced by the impact of any object or action on a surface.

Examples are footsteps, moving furniture, or dropping an item. The vibrations from impact noise travel through the vents onto other rooms.

The sound made from impact can be loudly transmitted through floor vents more than the ones above the door.

Impact noise is a little bit more challenging to address because of the energy produced upon impact with a structure.

Airborne Noise

Airborne Nosie Diagram

Airborne noise, as the name implies, is transmitted through the air. Sound waves travel through the air and create noise when they collide with a solid object.

Airborne noise mostly travels through door vents, along with the sound waves.

While impact noise travels downwards, airborne noise travels upwards. These are sounds coming from things like:

  • People’s conversations
  • Television
  • Music playing
  • Flushing toilet

Think of these noises as the sound effects you hear in a horror movie.

With these sounds traveling through a tunnel-structured vent, the noise is echoed.

What Causes Air Vent Noises

The inside of an air vent is made out of metal, making it prone for sound to bounce off and echo through its space.

Metal cannot absorb sound, which results in the noise being released through the vent openings.

In learning how to soundproof air vents, we need to consider these three things that amplify air vent noise:

  • The shape of the air vent
  • Number of walls inside the vent
  • The material the vent is made of
  • Position of the vent (ceiling, floor, or above a door)

Wrapping It All Up

Stack of white air vents

The air vent is one of the most difficult parts of a room to soundproof due to its tubing and opening. It’s also one of the main sources of unnecessary noise, especially if it’s a centralized HVAC system.

The processes mentioned above are surefire ways to soundproof your ventilation system. Feel free to combine some of them altogether to heighten soundproofing levels!

Get to know the complete layout of your air vents so that you could choose the best one that will work for you. Find a balance between good noise reduction and adequate airflow.

It’s up to you if you choose to get professional sound reduction help, and if not, you could always DIY your way through with the help of this guide!


Changelog:

July 12, 2021 – updated external links, removed affiliate links

July 2, 2021 – updated internal linking

June 15, 2021 – added changelog, fixed article format, updated internal linking, optimized content

About the Author

andrea_adams

Andrea has always been bombarded by the hustle and bustle outside her home. Living in the city doesn’t get any quieter. The never ending noise from construction, traffic, and dogs barking on the streets day in and day out drove Andrea to a breaking point.

For 3 years, Andrea committed herself to studying DIY hacks, performing soundproofing experiments, and installing noise-free solutions. Now, she lives a quiet life free of the stress from noisy environments.

She hopes to share this knowledge so that others don’t have to endure the noise reigning in their ears and live a peaceful, stress-free life.