how can suspended ceilings provide sound insulation?
441980
Sound is made up of compression waves propagated through air when these waves hit your ear they are what we call sound.  when they come in contact with a surface, depending on the makeup of the surface, energy can be absorbed or resonated or both.  If the energy resonates the material and no loss/absorption occurs then the sound will be the same on both sides of the surface (think of a membrane wrapped tightly over an opening like a drum, or ear drum for that matter which has little absorption qualities).  Because a naked/unmodified ceiling is rigid, it has resonant properties and the sound will permeate through the ceiling with some loss. Different surfaces have different amounts of loss/absorption, and some surfaces have excellent absorption qualities, such as off the shelf acoustical tiles, usually hung on a suspended ceiling (mostly because these materials have poor structural qualities and cant be built into the floor).  \nWhen in place the majority of sound energy is absorbed in these tiles and very little is resonated through them, thus sound insulation is achieved.  \nOne thing that needs to be pointed out is that ears are extremely sensitive over a wide range of sound powers, so much so that sound reduction is usually measured in decibels which is powers of 10. The interesting thing is that in the moderate sound power situations the brain has a hard time telling the difference between 10's of decibels, unless there is a point of reference.  And what is meant by this is suppose you are playing the drums in your basement and someone upstairs complains,  you add a false ceiling with some accoustic tiles and continue to play, and still you get complaints you may have lowered the sound that your neigbor recieves by many tens of decibels, but yet their brain still picks out the drums from their quiet environment.  At this point the solution is to go out and buy them something that makes noise, like a hepa-filter or fan, and give it to your neighbor and some how convince them that having it on all the times extends thier life.  Now and only now will the neighbor stop complaining about the noise.
138019
As I understand it, it is sound that is broadcast over a PA system (Like in an office setting), that actually neutralizes the noise that is ocurring in said office environment. It doesn't drown it out, in fact one doesn't even notice it. It is projected at a frequency that obliterates the frequency of the noise already ocurring in the room. Its supposed to help in the work environment.
404374
The critical barrier to insulate is the wall between the living area and the garage. You lose heat thru the wall.\n\nAs for the attic above the garage, that is a waste of money for the insulation. \n\nThink of the living envelope of your home needing to be protected and insulated. The walls and ceiling create this envelope. Some people try to increase their living space by modeling their basement and some by modeling the attic. You are fooling yourself if you think this added space is as equal in comfort as the original envelope. \n\nYou can cause more trouble than what it's worth when changing the attic. Cold air is suppose to circulate cooling and drying the moisture which escapes up thru the ceiling. Adding another insulated barrier prevents this from happening.
364559
I'm going to assume that you are asking which of the two materials you listed are best at absorbing sound vibrations.  There are many methods, the two you listed are valid, albeit a bit primitive, but the link that I have included below may help you much more.  (Cork soundproofing can be quite expensive, btw.)
239067
Could you mean phononics?  See the link.
590213
insultate it with soundproof foam
44224
Since your mystry noise question is already closed, I'm answering here.\n\nI think it is unlikely that your walls would resonate.  The table top seems a lot more likely to me.  The sound would be transmitted directly to the table top by the computer frame.\n\nTry setting the computer on the floor and see if that stops the noise.  If it does, then the resonance of the table top is it.\n\nIf you can't leave the computer on the floor, you need to physically isolate the computer from the table top.  Cut a 3/4" board to the size of your computer.  Put something that absorbs sound on the table top, the board on it, and the computer on the board.\n\nClosed cell foam rubber or plastic would be good to use.  You will find that in pipe insulation, "noodles" swimming pool toys, kick boards, and styrofoam sheets.
296388
if it's a ultrasonic weapon that produce a high pitch sound. i dun think you need any protection for it...coz you can't hear it. there's a frequency range for human ears.
192438
It absorbs pressure spikes.
517188
It is possible to encode sound into light, send it through space, then decode it back into sound.  You can do this by using the amplitude modulation of light.  Basically, you make the light "wiggle" and it then has a pattern of the sound vibrations.  See my sources for complete details.  It also explains step by step how to build such an apparatus.
333170
Keeps things from falling in the sample but allows the sample to vent to the air in the lab.
575618
I'd use lots of pyrotechnics, and surround sound to make myself sound booming. All you really need is fire and confusing sound.
623872
there is a lot of research on sound/acoustics here is a good source of information http://www.livesoundint.com/
197184
I do just for the simple reson that I can't stand silence. another alternative is using a fan. it will make just enough noise to break the silence. Good luck
470235
The previous poster is right.  It's particles in the air "vibrating" (caused by pressure differences) that enables you to hear.  That is why in space, which is a vaccuum, you cannot hear anything.  There is nothing to transmit those pressure differences to your ear.
37506
either sound, waves or air.
18286
If a lightning strike is a sufficient distance from the observer, sound from the strike will not be heard. These silent bolts are called heat lightning. Lightning bolts produce thunder, but the thunder sound does not travel all the way to the observer if the observer is too far away.\n\nThe movement of sound in the atmosphere depends on the atmospheric properties of the air such as temperature and density. Because temperature and density change with height, the sound of thunder is refracted through the troposphere. This refraction results in spaces of volume in which the thunder does not propagate through. For more information, please refer to the source