Sound deadening mat & what's MILsssssSc

I'm looking at the above materials : if they're stick to bedroom doors (where more than 95% of
the noises goes thru my daughter's room from my autist son's shoutings/wailings), will they
reduce more than 70% of the noise?

In particular I saw one in link below which has a specs of 200 MIL : what's this MIL & if the MIL
is higher, does it block sounds/noises more effectively?

Are those made in China ones as good in noise insulation?  They did not give any specs though

In cases where people has drums & loud musical equipment, I've heard they insulate their
rooms with certain materials.  Are these insulators from music industry as good as those
"sound deadeners" listed in eBay in blocking off sounds?
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sunhuxAuthor Commented:

Above link has a line (below) : so does this mean for 50mil, it will reduce 5dB & for 200mil, it will reduce 20dB?
Just one layer of GT MAT sound insulator will reduce up to 5 DB of unwanted noise

Among the list of sound deadeners listed in eBay link earlier, any recommendations?
David Johnson, CD, MVPOwnerCommented:
You would be better off using a sound deadening material that is specific to the sound range of the human voice 300 Hz to 3kHz.  The automotive sound deadening is designed with the engine frequencies in mind and the ability to withstand high heat

Are these insulators from music industry as good as those "sound deadeners" listed in eBay in blocking off sounds They are better.. Every 3db reduction is halving the level.
sunhuxAuthor Commented:
What's the Hz range of a kid shouting/crying/wailing?

Between the 50mil, 80mil & 200mil, which of them are likely to reduce the kid's noise better?
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sunhuxAuthor Commented:
I noticed tt when my autist son shouts/cries in the car (with windscreen l closed), we can't hear him from outside
sunhux I feel sorry for your predictament
Is the door hollow you could consider replacing the  hollow door with a solid door.
There is some really cheap tricks using foam and other insulation materials that wont cost you too much.
How To Soundproof A Bedroom Door – Do It Yourself 
MORE ABOUT SOUNDPROOFING DOORS – About Door Sweep Soundproofing
Thick curtains also work well.
Good Luck
David Johnson, CD, MVPOwnerCommented:
sound relies on the movement of air as a transport mechanism.  Take a look at a speaker when it is playing something and you will notice that it is vibrating. A car is a pretty good sealed container so the vibrations in the air don't get to the outside.  Higher pitched sounds are directional while lower pitched sounds (i.e. BASS tends to be omnidirectional and can also be transmitted by the vibration of solid materials i.e. walls.

Thicker can be better if everything is equal.
sunhuxAuthor Commented:
Our bedroom doors are probably semi-hollow: I've another EE article which the
experts shared: a certain degree of sound will still go through unless a layer of
vacuum covers the room.

In our case, the sounds/noises going thru the 6" thick concrete walls are negligible,
it's the wooden doors & I'm certain because when autist son shouts, I put my ears
on walls, floors, windows (facing out & door : it's always the doors that the sounds
came thru loud & clear

Looks like I'll source for acoustical curtains locally

There's some gap under the door & at the hinge, so the air vibration answer makes
I agree with everything David Johnson has said.

>>  what's this MIL & if the MIL is higher, does it block sounds/noises more effectively?

1 mil ==>  0.001 inch     So 200 mil ==> 0.2 inch.

Thicker is better.  If one sheet reduces noise by a factor k, doubling it should reduce it by k².
Two 100 mill sheets with a small gap between them might work better than one 200 mil sheet.

I know you have been working on this for a while.
What have you tried?  And what has and hasn't worked?

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Fred MarshallPrincipalCommented:
Depending on the layout of the rooms, walls, hallways, etc. you might also consider dealing with the question:
"How is the sound arriving at the door and are there ways to attenuate it at that point?"

I imagine you've considered the path leaving your son's room (e.g. door).

Hallway walls, ceiling and floor.  If you can get half the sound energy absorbed or deflected before it reaches the door then that may be helpful.

While likely not the cheapest approach, have you considered active noise cancelling?  It works best at low frequencies but that's where the isolation materials are least effective.  The idea is that there's:
1) a "reference" microphone at or near the source of the noise and
2) an amplifier and speaker between the noise and the "quiet zone" and
3) a microphone in the quiet zone for adjusting things.  
The output of the reference microphone is filtered / equalized so that the output at the quiet zone microphone is minimized.

Here's an example of a product that does that sort of thing.
sunhuxAuthor Commented:
>What have you tried?  And what has and hasn't worked?
I've tried rubber sheets stapled onto the doors : when my autist kid jumps on
the floor or the trampoline mat is sagging & the feet touches the floor when
he's using it, the neighbor downstairs complain & by placing these rubber
sheets on the floors, it helped but stapling onto the doors hardly help.

The Helos extreme earplugs are uncomfortable so girl is not using it.
The Howard Leights earmuff probably reduces by more than half but
she could still hear it.

I've just ordered from Amazon the white noise generator & Zac's soft
ear-plugs together with Trampoline ropes which ships free all the way
to my country (as it's above $125). hopefully she uses them) & it helps

White styrofoam boards on the doors: not that good
sunhuxAuthor Commented:

Is the above white noise generator (which is on the way) helps with noise cancelling?
I thought so too that after the earmuff, what my depressive/anxious girl is hearing are
the lower frequencies  noise
>have you considered active noise cancelling?  It works best at low frequencies but that's where
>the isolation materials are least effective

I could have gone to very costly contractors to get this done but I'm staying at this place
for another 1.5 years only, so don't want to invest in this but DIY first
A white noise generator is a masking device, which is not the same as active noise canceling.

You might do better with soft puffy insulation, rather than hard styrofoam.
Consider hanging a polyester bed quilts on a curtain rods or dowels inside and outside your daughter's door.  These are large enough to cover the door (sides and bottom).  

I see prices as low as $10, but I can't tell how puffy they are.
Fred MarshallPrincipalCommented:
The three fundamental approaches:

1) attenuation using sound deadening materials, etc.

2) masking with other noises so it's not so distinct (but it's still there)

3) cancellation with "anti-sound"; i.e. produce sound waves that are the opposite phase of the annoying sounds such that there is much less sound energy entering the "quiet space".

All 3 have their advantages.  
Attenuation with materials may be inexpensive and anything from easy to difficult to implement.
Masking works if the annoyance is due to not-so-loud but impulsive / very noticeable sound (this is why sirens are almost always transient - to be noticeable).
Cancellation works quite well and can work on a room or one might use noise-cancelling headphones that are adequately comfortable.

There is an entire field of study called "psychoacoustics" which deals with the psychological effects of sounds.  One reasonable question to ask is:
"Can this sound be reduced enough to reach satisfaction with ANY approach?  (This has to do with the person being annoyed).
Wouldn't it make better sense to do this sound deadening on the son's door first.
Since it is that bad I'd also have a talk with him about respecting others.
sunhuxAuthor Commented:
Hi Merete,
My autist son has a low IQ & even the psychiatrists, psychologists & therapists could
not get him to keep quiet or calm when he's agitated.

>This has to do with the person being annoyed
The person being annoyed (ie my girl) is very sensitive even to her autist brother's
slightest noise
Fred MarshallPrincipalCommented:
sunhux:  Yes, I understood that the person being annoyed is your daughter.  Saying that she's "very sensitive even to her autistic brother's slightest noise"  rather makes the point:  
"Is it possible or likely to solve this problem by technical means?"
I know that you must try....
Thanks for explaining  sunhux I fully understand now.
This is most difficult for you your kind of caught between the two.
I have experienced being with autistic people but not young children?
The real solution here is to separate them, use the rooms further apart if that was possible.
Move daughter to basement or other end of the premises a room further away.
Replace both doors with solid sound proof maybe the simplest and least amount work for you.
Using a foam core door or an interior door designed for soundproofing would be a good option.
Then ensure there is no gaps at the bottom.
Helping your daughter to understand would also assist your already over burdened nerves.
Educate her take her to a workshop.
All the best to you.
regards Merete
sunhuxAuthor Commented:
>Wouldn't it make better sense to do this sound deadening on the son's door first
To an extent yes but my son spends most of his awake times in the living room
or common areas in the house, not in his bedroom.

>solve this problem by technical means?"
What's the tech means?  Have tried to home my son in a nearby home but
usually such homes are only for such special-needs people whose parents
are not around or abandoned by their relatives & very extreme justifications
is needed.  I tried but did not manage to home him

Then place my girl in a school hostel?  It did not work out : hostel won't take
her in for fear of her 'mental' condition.

Yep, replace the door will cost me a couple hundred dollars
Fred MarshallPrincipalCommented:
As I said, I know you must try the technical approaches.  I hope it's not an exercise in frustration more than you already have to deal with.  At least you've seen the range of possibilities.  
I don't know the cost of various noise cancellation products other than headphones.  But the projector stuck on the window might just as readily stick on a door.  That would be a departure in the type of door you'd use though.  For one of those things you'd want the door to be a projector and, thus, rather flexible.  Composite carbon fiber sheets have been used for this with multiple speakers attached.
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