It's almost sound proof inside a car : apply similar idea to sound proof a room?

I noticed that even if my autist son shouts at his loudest while inside the car (with the car windows
closed), we can't hear him.

As he makes a lot of noise inside his bedroom or when he's in the living room, it affects/disturbs
his NT sister who is in another bedroom & are often 'super-annoyed' by his wailings/noises

In another EE thread, someone has suggested using styrofoam with bubble wraps but I wud say
this cuts out only about 50% of the noise.  

What makes the car soundproof?  Thought of applying the same on the bedroom's doors as I'm
certain the noises travel thru the wooden doors (not via the thick walls & glass windows) : I can
even feel the vibrations of the noises when I put my ears on the wooden doors.

I can certainly engage professional anti-acoustic contractors to soundproof but I want to DIY
currently as I may not stay long at this house.

I did buy ear plugs for my girl but she doesn't feel comfortable wearing it most of the times
Who is Participating?
John HurstConnect With a Mentor Business Consultant (Owner)Commented:
You can soundproof a room by insulating the walls (interior walls) and using a heavy solid wood door. Make sure the door is snug and well fitting and the vast majority of sound will be completely muffled. You might put some rubber (plastic) gaskets around the door in such a way that does not impede it opening and closing.

You can go to greater lengths but the above two things are easy to accomplish.

Car doors (my car doors) have double gaskets around the edges.
Dave BaldwinConnect With a Mentor Fixer of ProblemsCommented:
A car is mechanically disconnected from the environment through the interior padding but also through the tires which do not transmit sound well.  See here for more info:
A proven path to a career in data science

At Springboard, we know how to get you a job in data science. With Springboard’s Data Science Career Track, you’ll master data science  with a curriculum built by industry experts. You’ll work on real projects, and get 1-on-1 mentorship from a data scientist.

viki2000Connect With a Mentor Commented:
Here is my short experience.
I had the chance to enter in a soundproof room, not bigger than 3m width, 5m length and 2.5m height. Was during last year in a visit in Belgium to a company specialized in piezoceramic speakers.
They used the room to characterize the speakers in  frequency bandwidth with a very expensive specialized microphone attached to a digital system with PC’s and specialized software for audio analysis.
While I as inside, I had to raise my tone in order to be understood by the other 2 persons in the room at 2 m distance from me. It was an amazing experience, almost similar as the words were stopped, decelerated, attenuated in the air and did not reach the other persons. Also the sound from my mouth did not reach my years in the same way.
All over the walls, including the floor and the ceiling were mounted blocks of materials similar with a sponge, but special made for sound attenuation with 3d shapes which looked as pyramids/cones.
What I have seen was something like this:
As conclusion, you have to put on the walls/ceiling special materials as for example:
BillDLConnect With a Mentor Commented:
Hello sunhux.  I remember your other question about trying to sound proof rooms in your house.

Sound transmission is quite a strange thing.  High frequencies are very directional and don't travel as far or as well as low frequencies which are able to bend around reflective surfaces.  That is the reason that you can hear an explosion from far away.  It is also the reason that you can hear the "boom, boom" bass frequencies (drums and bass guitar) from a rock concert many miles away, but the higher frequencies like vocals and guitar don't reach you.  All these young guys who install huge speakers in their cars can be heard before you see them because the extreme bass frequencies from the sub-woofer speakers not only escape more easily from the car, but they also vibrate the metal bodywork of the car and it begins to behave like a speaker.  The higher frequency sounds are reflected back into the car and eventually dissipate.

The frequencies of a human voice aren't low enough to be considered low frequencies, so generally will be repeatedly reflected off hard surfaces in a closed room until they fade out.  Some of the frequencies will make some of the hard surfaces vibrate and transmit some of the sound through to the other side of that surface.  With normal everyday sounds like traffic, speech, etc, you need to put a layer of padding on hard surfaces to absorb the sound and stop it from being conducted through those surfaces, and block air gaps with something that absorbs the sound.

When you walk into an empty house or apartment that is for sale and has no furniture, carpets, or curtains, when you talk there is a lot of echo (reverberation) because there are so many hard flat surfaces to reflect the sound, but no odd-shaped soft furnishing to absorb any of the sound waves.  Your voice will usually sound louder inside the room because of this, but it doesn't necessarily mean that your voice will be louder outside the house or in adjacent rooms.

Ideally you need something sandwiched between two layers of wall board to prevent sound waves from being conducted by the hard building materials, and you also want an uneven layer of soft material on large flat surfaces to absorb sound that would be conducted through the wall and reflected from it.

A guy who I work with recently converted the large attic of his semi-detached (duplex) house into a bar and entertainment area.  He was concerned that the TV, Hi-Fi, and loud drunken voices would disturb his neighbour through the wall and one floor below the attic.  Based on advice that I gave him, he placed rubber padding on top of the support joists before screwing down his new flooring panels, then carpeted the new floor.  When building walls around this new living space he used the double layer Gyproc (drywall, plasterboard) that has a honeycomb of cardboard in between the layers of plasterboard.  He stuck thick (maybe 1.5 inch) polystyrene foam (styrofoam) panels onto the outside of the walls to provide thermal and sound insulation.  The wall boards were screwed onto the wooden beams in the attic so that the polystyrene foam acted as a form of padding between the new wall panels and the wooden beams.  On the wall that was closest to the brick wall between the two houses he hung a very large ornate rug that covered almost all of that wall.  The neighbour cannot hear anything from this guy's new man cave even when he has about 8 people up there playing music and getting drunk.

It's pretty hard to convert an existing room like this, especially if you are in a rented home where you can't start making false walls with baffles between them, so the nearest you can get is by improvising with temporary wall coverings, such as heavy drapes, etc, and by getting as much padded soft furnishing into the room as possible.
nickg5Connect With a Mentor Commented:
Our experiences are with sounds that can get as high as 100 decibels in the house. Check the decibel level for your child's loudest yell.

We tried various things for the noise outside the house. Nothing worked well. We considered thick foam to fully cover the window or even to brick in the entire window.

The two bedrooms are side by side and even when one person is speaking in a low tone on their Skype, they can still be heard in the next room. The walls and insulation are the standard but don't block the noises.

We also considered a high brick wall for the outside noise and we were told that even a 100 foot high brick wall would not stop the noise. It would go over the wall.

Ear plugs did not work either even the kind for industrial noises. The plugs themselves created other uncomfortable sounds like ears ringing and a sound similar to what you hear when you listen to a large sea shell which is called a conch. The sound there is resonance.

The only relief we get from the outside noises all night are a pair of noise deterring head phones but they are not 100%. Maybe 80% noise reduction and the ringing and sea shell type sounds are mostly eliminated.

I think you have very limited solutions for your child.
We found out that even a 100 foot high concrete wall outside and 150 feet long would not stop the outside noise.
We have a lights out time for all members or guest and we have to utilize other methods to get by with the outside noises.

Here is a chart of decibel levels and it looks like a screaming child can reach over 100 decibels.

20 dB ticking watch
30 dB quiet whisper
40 dB refrigerator hum
50 dB rainfall
60 dB sewing machine
70 dB washing machine
80 dB alarm clock 2 feet away
85 dB average traffic
95 dB MRI
100 dB blow dryer
105 dB power mower, chain saw
110 dB screaming child
120 dB rock concert, thunder clap.
130 dB Jackhammer, jet plane (100 feet away)
you can also insulate in layers, in order to get better results
i mean: first insulate the room, then the house, or other rooms around it
Remember, of course, that you still need to breathe.  We need oxygen to survive, and where there is an air gap sound can get out.  People can show signs of mystery illnesses if they don't get enough oxygen, hence the reason (actually a myth) for medical staff removing plants from hospital rooms at night.
SunBowConnect With a Mentor Commented:
> What makes the car soundproof?  Thought of applying

Agree. Main method is the sealing of door and window. Within home the bottom of door likely has the worst seal. Light may be seen seeping through. Rubberize doorway, the door itself may need to clear carpet. Next is the reduction of continual flat surfaces, add curves and things that are soft/absorbant. You may want to replace door. Likely they are flat and hollow. Use solid door(s) preferably that are not flat but have some design with bevelling.

Double/triple pane the glass. Hang curtains & drapes over windows, look for other places to hang cloth and carpet well.

The pyramid shapes work well (spongy, with lotsa holes, light as styrofoam). Maybe do entire ceiling.

Remove all objects having large flat surface - table, chair, dresser, etc. For 'homework', maybe a desk where top is slanted, not horizontal will work better.

How about some tapestry for walls, maybe adding a throw rug or two, family pet may like that. Seek other ways to add/hang cloth.

> I want to DIY currently as I may not stay long at this house.

Then concentrate first on what you can take with you, like curtains and drapes and throw rugs (@door), place window replacement at bottom of list, but as among things to check out for among candidates to move to.

Also - best overall, is find way to get him to shut up. Maybe some pets and crayons and music he can favor, or produce white noise. Soft 'doll' like bear, try to identify some animal or shape or texture or color of preference. Don't neglect to try some other doctor who may identify medical reason he may be screaming about. Do again after moving.

Get him alternate choices for bedding - think of Linus & blanket. I personally prefer a large feather pillow. He may prefer a bean bag or some balls.
sunhuxAuthor Commented:
Thanks a lot for the wonderful responses.

Yes, BillDL replied to my previous post.

> Ear plugs did not work either even the kind for industrial noises
Got one of the better plugs from Amazon, Hearos & it indicated sound reduction of 30dB & surprisingly
my girl can still hear my autist boy's shouting in the living while wearing the plug (& she's in her room).

>I had the chance to enter in a soundproof room, not bigger than 3m width
Viki2000, was the above room air-tight?  I did call out a local dealer who has a similar-looking
wavy foams & the dealer told me it will cut down about 30-40dB only.  I guess my autist son's
wailing is at least double of that : can still hear his voice with the Hearos ear plugs (not the
soft one but the one that blocks noise better) plus a Howard Leight earmuff :
>>   I did call out a local dealer who has a similar-looking  wavy foams & the dealer told me it will cut down about 30-40dB only  <<  industrial top quality is not found easily, and probably the local dealer doesnot have it
viki2000Connect With a Mentor Commented:
was the above room air-tight?

Not really. It had obviously a door, but not something very special. The door had on it that foam with cones-like shapes.
Of course I was not outside the room while somebody inside would have tried to scream in order to test your similar situation. But the effect noticed inside the room was amazing, I never experienced something like that before.
Dave BaldwinFixer of ProblemsCommented:
You don't want something as quiet as an anechoic chamber.  The lack of echo will cause mental and physical problems if you stay in there too long.
BillDLConnect With a Mentor Commented:
Another thing to consider is whether there is the possibility that your son has tinnitus:
This condition, particularly the high-pitched squeal-hiss type, can be worse in total quiet.  Some sufferers are helped by always having some amount of background noise, such as quiet music.  It might be worth checking whether your son has tinnitus before you try and exclude all sound coming out of his room, because that would also mean that you would be excluding sound coming into his room.  Who knows, perhaps this could be contributing to his compulsion to shout frequently, although it is most likely to just be part of his Autistic condition?
Then the best would be to ask the doctor about such soundproof room, isn't it?
A General Practitioner doctor generally wouldn't have the experience to make any recommendations. These days GPs don't even feel a sore elbow or knee to try and find out what is wrong, they just look at it, prescribe pain killers, and tell you to come back if the pain persists.  It might be the best way to get a referral with a Consultant in the relevant field.
sunhuxAuthor Commented:
>You don't want something as quiet as an anechoic chamber
The above is not an issue: windows of my autist son's room opens out to the other side of the building
while my girl's windows is on yet another side of the building & I'm 100% sure I can't hear a thing via
the windows.  My girl has some music turned on as well.
sunhuxAuthor Commented:
My son doesn't have Tinnitus.

Besides my son's voice, the screaming nanny's voice is probably (in fact higher pitched) louder.
She's getting sort of mental distress from looking after my son who would sometimes pull her
hair or scratch her
Isn't it cheaper the change the nanny?
SunBowConnect With a Mentor Commented:
> windows of my autist son's room opens

Main issue is they are flat surface = reflective, and may be able to vibrate, not conducive to add-on like foam. Curtain can absorb and diffuse and be portable. Car windows have curvature.

There' also insulation you can squirt into door and wall. Turns from liquid to foam. Wall may be accessible from above. Not sure how to tell you to do door. Maybe you need to drill a couple more holes.

> My girl has some music
 find music that soothes him, may be classical, or jazz, or lullaby - why guess too much, he's more than underdeveloped, he's uniquely overdeveloped. Maybe operetta. Maybe like Gilbert & Sullivan: The Mikado, The Pirates of Penzance.
Thank you sunhux
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.