How to Design a Sound-Proof Box?

[screamingman]

I desire to build a box that is sound proof that would be only slightly larger then my head, which I could scream as loud as I possibly could, yet the outside world would barely be able to hear, or not be able to hear at all (as little as possible). I have almost no knowledge of physics (only an intro mechanics class at a community college--I am taking calc based mechanics E&M, and waves next year), and so I did not know where to put this question. Any advice, ideas or information that could be provided to benefit the project are greatly appreciated! The best advice would be what to use, and why to use it, although anything is truly and genuinely appreciated!

Thank you!

(if anyone would like reasons for the project, I will post, but I did not want to waste peoples energy with potentially undesired, superfluous material).

 

[Simon Bridge]

You'll need to experiment a bit - the usual starting place is textured foam rubber: the walls of your box must absorb sound.

What you end up with is limited only by your budget and how silly you are prepared to look.

 

[screamingman]

Thank you for giving me a take-off point. And looks/judgements have never effected me.
Is textured foam rubber more potent at absorbing sound then carpet?

 

[Bobbywhy]

Of course absorption of the sound with textured foam will reduce your scream intensity. But there is another method, if you're willing to invest in some technology: noise cancellation. This method could, in theory, completely cancel out whatever sound you can produce. Bose, for example, sells Noise cancelling headphones that operate on the principle. I suggest you do some searching (aka: research) into this as a possible solution.

 

[Simon Bridge]

Is textured foam rubber more potent at absorbing sound then carpet?

depends on the details of the material. Just several layers of thin/stiff card separated by air can have a big damping effect.
http://www.ehow.com/info_8050937_materials-absorb-sound.html (lots of relevant links)
http://info.acoustiblok.com/acoustiblok-products/quietfiber/ (commercial sound absorber)

I've seen a soundproofed container about head size that was basically a plywood box with louvre baffles (you'll need some way for air to get in and out :) ) lined with acoustic foam. It was designed to house a noisy pump.

Some noise will still get out for anything reasonably portable - but a thick polystyrene cup lined with foam and an outer-shell of thin plastic that just fits over mouth and nose could knock out most of the sound from yelling - so you may want to consider a composite strategy.

Technology can be as sophisticated as you like - i.e. the sound cancellation mentioned - depending on how deep your pockets are ;)

I take it just duct-taping your lips shut is out of the question?

 

[technician]

Great physics project and great fun. What you are after is known as an anechoic chamber.
As well as rubber foam egg boxes make a great sound proofing liner. They are absorbent and the irregular surfaces produce scattering and improve absorption...also almost cost free.
BE CAREFUL ! The absorbed sound energy could cause the head ware to heat up !

 

[sophiecentaur]

Great physics project and great fun. What you are after is known as an anechoic chamber.
As well as rubber foam egg boxes make a great sound proofing liner. They are absorbent and the irregular surfaces produce scattering and improve absorption...also almost cost free.
BE CAREFUL ! The absorbed sound energy could cause the head ware to heat up !

A fan could help with the cooling.

In addition to the need for a good loss mechanism (foam / fabric) it would also help to have a good acoustic mis-match at the boundary with the outside air - that would involve a rigid, dense envelope. Any anechoic chamber worth its salt will have thick concrete walls, for this reason.

A thick, steel domed helmet would work (Diver's Helmet job). A lighter and less unpleasant solution could involve two or three thick polycarbonate shells (double / triple glazing), which would allow you to see and be seen (but not heard). A curved surface would flex less and, so, transmit less sound energy. You would need a very good acoustic seal round the neck, two long in/out tubes would allow fresh air to circulate as you wouldn't want a lot of tidal air in the helmet.

[EDIT: As I sit here I can see a decorative 'chamber pot' on a shelf. It got me thinking of a cheap solution. It may be worth while looking for a glass goldfish bowl. It would be ideal material, in many ways - just a bit heavy, perhaps.]

 

[CWatters]

What seems to work well are layers of a material with relatively high mass (drywall or plywood?) separated by layers of sound absorbent material (soft foam/egg box foam?). The trick is figuring out how to support/separate the high mass layers without bridging the sound absorbent layers.

Your neck will unavoidably bridge the sound absorbing layers.

PS Presumably this forum logs IP addresses (at the very least) so we can be sure you don't plan to put anyone else in this :-(

 

[technician]

A fan could help with the cooling.

In addition to the need for a good loss mechanism (foam / fabric) it would also help to have a good acoustic mis-match at the boundary with the outside air - that would involve a rigid, dense envelope. Any anechoic chamber worth its salt will have thick concrete walls, for this reason.

A thick, steel domed helmet would work (Diver's Helmet job). A lighter and less unpleasant solution could involve two or three thick polycarbonate shells (double / triple glazing), which would allow you to see and be seen (but not heard). A curved surface would flex less and, so, transmit less sound energy. You would need a very good acoustic seal round the neck, two long in/out tubes would allow fresh air to circulate as you wouldn't want a lot of tidal air in the helmet.

[EDIT: As I sit here I can see a decorative 'chamber pot' on a shelf. It got me thinking of a cheap solution. It may be worth while looking for a glass goldfish bowl. It would be ideal material, in many ways - just a bit heavy, perhaps.]

I am inspired...I think I will have a go at making one...I will start with egg boxes and I might fit cooling fins of some sort.
As an extension I think I will instal mini speakers so that I can listen to my I- pad and yell my head off without disturbing anyone.
I will post a photograph if it works ( I am surprised the infamous Sheldon Cooper has not beaten us to it)
Screamingman...you are an inspiration

 

[256bits]

Put on a space helmet and take the next rocket to space. Out there you can scream as much as you want and nobody will hear you.

So you build a sturdy space helemt facsimilie, and suuround that with a globe. In between evacuate the air and you have your "Screaming While Space Walking Device" ie (SW)^{2}D, which even gives it a cool name and artist merit.

Just make sure everything is failure safe.

 

[screamingman]

Thank you all for the incredible answers! I just got my wisdom teeth out, but have been trying to wade through all of the incredible suggestions and responses (I am unsure of some of the terms used, etc.). I will post back a substantial, detailed response after I understand all/some of the suggestions better.

 

[cjl]

BE CAREFUL ! The absorbed sound energy could cause the head ware to heat up !

Not likely. The amount of energy contained in even extremely loud sounds is pretty negligible.

 

[sophiecentaur]

Not likely. The amount of energy contained in even extremely loud sounds is pretty negligible.

No chance of a shout powered radio!

 

[SteamKing]

Just step back into the closet and close the door. You can scream all you want.

 

[technician]

Not likely. The amount of energy contained in even extremely loud sounds is pretty negligible.

Negligible is not zero! There will be some heat energy...no harm in pointing out potential hazards.
The threshold of pain is about 130dB which is about 1 watt/ m^2

 

[sophiecentaur]

Negligible is not zero! There will be some heat energy....no harm in pointing out potential hazards.
The threshold of pain is about 130dB which is about 1 watt/ m^2

Hardly a 'hazardous' quantity - compared with the heat radiated from and breathed out by his body. You have to quantify an effect before you can call it a hazard.
Any sound damage to the ears from shouting will be self limiting.

 

[technician]

Hardly a 'hazardous' quantity - compared with the heat radiated from and breathed out by his body. You have to quantify an effect before you can call it a hazard.
Any sound damage to the ears from shouting will be self limiting.

I do not think that you have to quantify an effect before it is identified as a hazard! First you have to identify it as a POTENTIAL hazard.
You may need to quantify it to be able to deal with it.
I did quantify it (unlike 'negligible') he has just had his wisdom teeth out...130dB scream...perhaps a bit extreme but definitely quantified.
1W/m^2... I will try to come up with a temp increase. Which will probably turn out to be negligible

 

[cjl]

I do not think that you have to quantify an effect before it is identified as a hazard! First you have to identify it as a POTENTIAL hazard.
You may need to quantify it to be able to deal with it.
I did quantify it (unlike 'negligible') he has just had his wisdom teeth out...130dB scream...perhaps a bit extreme but definitely quantified.
1W/m^2... I will try to come up with a temp increase. Which will probably turn out to be negligible

130dB is past the threshold of pain and would cause immediate hearing damage. It's a rather unreasonable volume to be using, and even so, the power is negligible (the exact temperature increase will depend on the thermal characteristics of the box though). The amount of heat added to the box simply from the user's body heat will be much greater than the sound power itself.

 

[berkeman]

Hmm, I just had a sinister thought. What if the OP is building this thing to more effectively hold somebody hostage... Sort of a new form of a gag, but without the breathing difficulty issues.

 

[solar71]

You can not build a 100% sound proof box for your head. 95% maybe.
But don't forget the sound you make in you voice box can't be completely eliminated.
This is because some of the sound will reverberate though you neck and down.
So if your box does not cut your head completely off it can't completely silence you either.

 

[Simon Bridge]

Hmmm...
Potential Hazards:
1. energy from the noise absorbed being re-radiated as heat
2. alien races mistaking you for their leader
3. suddenly becoming extremely attractive to the opposite sex (due to removal of repulse effect of face)
4. suddenly becoming extremely attractive to the same sex, see above.
5. being mistaken for a hive by a passing swarm of bees
6. heat from body being trapped in the box
7. ridicule
8. possibility of being trapped
9. possible suffocation
10. possibility of being committed to an institution (psychiatric, ecclesiastical, a university, other...)

... when considering possible hazards, it occurs to me that it is a good idea to also have some idea of how to rank them for further investigation :D

 

[technician]

Hmmm...
Potential Hazards:
1. energy from the noise absorbed being re-radiated as heat
2. alien races mistaking you for their leader
3. suddenly becoming extremely attractive to the opposite sex (due to removal of repulse effect of face)
4. suddenly becoming extremely attractive to the same sex, see above.
5. being mistaken for a hive by a passing swarm of bees
6. heat from body being trapped in the box
7. ridicule
8. possibility of being trapped
9. possible suffocation
10. possibility of being committed to an institution (psychiatric, ecclesiastical, a university, other...)

... when considering possible hazards, it occurs to me that it is a good idea to also have some idea of how to rank them for further investigation :D

I would add:
11. Being taken seriously

 

[bahamagreen]

Low tech is best here... just need about four pillows and a closet with a door.

A good scream is about 5 watts.

 

[sophiecentaur]

I do not think that you have to quantify an effect before it is identified as a hazard! First you have to identify it as a POTENTIAL hazard.
You may need to quantify it to be able to deal with it.
I did quantify it (unlike 'negligible') he has just had his wisdom teeth out...130dB scream...perhaps a bit extreme but definitely quantified.
1W/m^2... I will try to come up with a temp increase. Which will probably turn out to be negligible

"Potential", related to the thermal hazard (which was what my post was about)?? Even less of a potential hazard than walking into a door whilst wearing the helmet, perhaps. Surely one of the essential aspects of the Scientist / Engineer is a good appreciation of the orders of magnitude of the variables involved. We would not go along with the MMR nonsense, for instance. Is it not obvious that the amount of 'mechanical' energy involved must be way below the existing thermal energy flow? In fact, the "potential" danger is seriously near zero. The figure for a 'loud shout' from bahamagreen is 5W (very believable). Bearing in mind that you can shout for only a few seconds, it should be obvious to anyone that the total sound energy involved would be a fraction of the thermal energy in the expired air during the shout and which would have to be flushed away (along with the CO2) in any serious helmet design.

 

[berkeman]

I would add:
11. Being taken seriously

12. Shortness of breath (SOB) and serious side ache from LMAO

 

[Liocha]

Hi Screamingman,

Have you gotten anywhere with your scream box project?