Blocking out low-frequency noise is one of the most difficult tasks in soundproofing techniques.
Why? Because you need to understand how low-frequency sound is produced in order to know the steps to keep them from entering your room.
Though there are a ton of soundproofing tips and materials you can use, it is better to focus on where low-frequency noise is coming from.
Sounds that hit the scale on a range of 10Hz to 100Hz are low-frequency noise.
Examples of low frequency are sounds coming from generators, furnace motors, truck engines, pumps, concrete drill, bass guitar, air conditioner and freezer hum, power plant, and many more. Most often, low-frequency sound travels within the floor and walls.
Understanding low-frequency sound is a way of uncovering the technique of how to block bass noise.
Those thumping noises coming from your neighbour’s room, especially from a shared apartment, and the continuous humming and beating of their musical instruments or the rumbling noise of their old washing machine will pound your heart more than your ears.
Though these sounds may not seem really hurting, the lowness of the frequency sends drills to their heads for some people. Such a vibrating effect is not healthy.
Even the constant humming of your furnace motor in the basement is intolerable.
What do you know about low-frequency noise? For that to be understood, it is better to compare low-frequency sound to high-frequency sound.
In the world of sound, we use hertz (Hz) in measuring the unit of frequency. Sound travels in waves. Concerning frequency, Hz is calculated based on the number of times that a sound wave repeats itself.
So in low frequency, sound waves travel slower than high-frequency sounds, making them inaudible to human ears since their ears can only receive the sounds between 20 Hz and 20,000 Hz.
As for animals, they can hear sounds lower than 20Hz, known as infrasound, which is beyond human’s capacity to hear, because these are very low to the human ears.
That’s why animals perceive more of an incoming phenomenon because they can sense the low frequency noise coming from a long distance.
In comparison, the high-frequency sound represented by short-wavelength travels faster than low-frequency sound characterized by long wavelength. Thus, the low-frequency sound is more felt than heard.
PRO TIP: Sound is often interchanged with noise. However, they are two different things, as the latter refers to sounds that are inappropriate and unwanted in a particular environment. That’s why they are called unwanted noise.
Sound Level Chart
|Source of Sound||Decibel (dB)|
|Jetplane (50 m)||140|
|Amplified rock and roll (disco) (1 m)||120|
|Chainsaw (3 feet)||110|
|Loud singing (3 feet)||75|
|Vacuum cleaner/food blender (3 feet)||70-75|
|Whisper (3 feet)||30|
|Threshold of hearing||0|
Low frequency noise is typical, especially in crowded environments. Urban environments produce background noise that seems to become familiar to the human hearing.
These sources are artificial sound sources, classifying them as noise depending on the individual’s pervasiveness and noise exposure and level of acceptance to the type of noise.
Examples of low-frequency noises are:
- Aircraft passing
- Industrial machines/mining
- Road noise or traffic noise
- Wind turbine
Though they are considered low in frequency, the intensity appears to impact the auditory senses significantly.
The rattling and vibrating effect of low frequency noises equates to the loud noise of high frequency noises brought by high-pitched squeaking sounds that are relatively irritating.
Thus, we find ways to block sound waves to prevent further disturbance, high or low frequency. But in this article, we focus on soundproofing techniques to ward off low frequency noise.
1. Find out the Noise and Source
We cannot solve a problem without tracing the source. Finding out where the low frequency is coming from saves you time, effort, and money. And it gives you more satisfaction once you identify the culprit.
What do you do?
- Check your appliances like refrigerators, furnace blowers, exhaust fans, and similar items that produce humming or vibrating sounds.
- Get near the walls or sense the sound from floors. If you feel any vibration, try to listen carefully and know where the source is.
2. Use Bass Traps
Bass traps absorb sounds producing low frequency, thus, “bass frequency.”
Bass traps are acoustic foams that you can install on the areas you feel there’s much more vibration than anywhere else. If the sound is coming from the boiler room, know where this is situated in the house.
You have a number of options online for the acoustic foam you need.
Most boiler rooms house the HVAC system in a basement. So, it is advisable to place insulation pads across the ceiling (which is beneath the ground floor) or get sound dampening materials to place near the components of the noisy furnace motor.
3. Add Drywall as a Noise Barrier
Build additional soundproofing elements to the drywall to reduce the sound going through that wall. Though drywall in itself helps in muffling sound, it depends on the sheet laid.
Drywalls tend to absorb vibration and allow the transmission of sound waves through the air in between.
You can add another layer of acoustic panels that will serve as insulation for the air cavity in the middle to correct this. That layer should have a thick mass for it to be sound absorbent and resilient against vibrations. Another option is to spray cellulose to block holes.
Low-frequency noise source travels easily through walls, as explained. That’s why having drywall with thicker mass, insulation implements, or attaching lightweight fiberboard sealed with a flexible sealant are effective ways to ward off low-frequency noise.
4. Soundproof Curtains
Whether your wall has a window or none, hanging soundproof curtains is an effective means to reduce low frequency noise.
The weakest spot in your wall that is highly impenetrable by sound is the windows. Buying soundproof curtains will block off the noise on areas like the window edges and gaps.
Soundproof curtains are technical fabrics that absorb sound and light. You can choose from the number of soundproof curtains sold online.
5. Soundproof the Room
There are a thousand and one ways to soundproof a room. If you are annoyed and don’t want to be bothered by the noise coming from your brother’s music room (even if that room is soundproof) just next to your room, you can do your soundproofing by any of the following options:
- Using soundproofing sealant when adding a layer to your drywall
- Installing acoustic plasterboard on the existing wall
- Adding mass-loaded vinyl or more commonly known as MLV, between the walls. MLV is a sound-protective material that is flexible, which is also suitable for covering ducts and pipes. They can also be used on floors and have them painted if you don’t want the monotonous grey color, or cover it with a rug instead.
- Adding acoustic tiles. Tiles aren’t as flexible as LMVs, but they are effective sound blockers, especially if you intend to convert your room into a recording studio. They not only reduce the transmission of sound from the outside but enhance the sound in the room.
- Use carpets to add sound insulation against vibrating hardwood floors.
6. Build a DIY Window Plug
These sound-reducing implements are practical if you don’t want sound entering your room, more commonly known as window inserts.
If the noise is coming from a separate space from your room or outside the home, soundproofing window plugs work by stopping noise traveling through even the slightest gaps in the windows.
Window inserts use a compression system to fit the edges of the window perfectly.
Commercial window inserts are made of acrylic material, can withstand sound pressure, and are better than glass in blocking noise.
In line with weatherstripping, your window plugs are perfect for reducing outside noise from coming in.
Although window plugs are not ideal sound blockers, they are efficient tools in casting out loud sounds such as sirens, power drills, truck engines, and the like.
PRO TIP: The difference between sound-absorbing and sound-reducing objects is that the former is effective in a space where the sound is generated within to lessen the echoing effect. If the sound is coming from the outside, the soundproofing implement is effective in noise reduction.
7. Seal Any Gaps
Use specialized sealant along with soundproofing materials you want to enforce on walls, floors, windows, ceilings, and doors.
Seal the gaps and corners with glue to prevent airborne sound and lessen the impact of noise even the insulators couldn’t block. Even tiny holes and cracks around light switches and sockets are essential to have sealant to achieve an ultimate soundproof space.
7. Use soundproof Blankets
Hearing a low-frequency sound just because there is construction going on nearby in your village, or your neighbor is hosting a wild party, you can hang soundproof blankets to control the vibration on walls and floors.
Soundproof blankets work the same way as soundproof curtains, and they can be temporary. They are also perfect for hanging on walls with their quilted finish, making them thicker and appropriate for low frequency sounds.
8. Use White Noise Machine
White noise machines are initially intended for people having a hard time sleeping, but they can help block low frequency noises around.
White noise with reduced higher frequencies is called pink noise, and brown noise lowers even more.
A white noise device produces a sound that focuses on low frequency sounds that affect people’s sensory perceptions. Sounds like crashing waves, chirping birds, rain, thunder, and more promote an ambient room environment for quality sleep or study.
White noise machines help in reducing the sensory impact of the bass. They are helpful if you get noise coming from outside your room that’s disturbing.
It just helps to replace that with a constant repetitive and relaxing sound that you can choose.
Somehow it can. Though low-frequency sounds aren’t that loud and more apparent than high-frequency sounds, they have an effect on one’s health. Some people are sensitive to low frequency sounds, making them nauseous and dizzy, and some can’t even sleep.
Since most white noise machines are not low-frequency noise blockers, they are not excellent for eliminating low-frequency sounds. Also, the noise installed on most white noise machines is made up of both low and high frequencies.
It only masks off the irritating sound by sending off ambient sounds to stimulate the brain or convincing it by having the artificial but nature-based sound blend with the low frequency noise that seems to drill one’s head.
Do Earplugs block low frequency?
If your ear plug or ear muff has a low-frequency noise cancellation rate of 22 dB to 33dB, they can only block the noise of that range.
Low-frequency noise examples given here step on high-scale decibel rates. Meaning, foam earplugs can only reduce low-frequency noise but not stop them completely.
Noise-cancelling headphones help in controlling sound pressure levels if soundproofing implements are not enough.
Blocking out low-frequency sound can be more complex because it will depend on how much you understand low-frequency sound waves, the difference between high and low-frequency noise, the examples, and your capability to experiment with sound insulation, noise reduction, and absorption.
Ultimately, it is your health that matters. If you feel stressed and are experiencing the intolerable noise level brought by low-frequency sounds, soundproofing is the best solution to achieve your peace of mind at home.
Robert is an electronic engineer with more than five years of experience with a solid affinity for helping people reduce noise. He writes about these silent home appliances and easy soundproofing measures to help everyone avoid the negative effect of extended exposure to high noise levels.