Contrary to popular belief, sound treatment and soundproofing are not the same process. Sound travels through large spaces as well as very small spaces and travels through walls, floors and other materials you would think would stop sound waves. When sound waves hit solid surfaces that reflect the majority of those sound waves, you have what is called reverberation. Reverberation is basically all of the echoes in a room combined, and in small areas, those echoes usually do not sound like an echo you would hear in a long hallway or large space like a gymnasium but instead a collision of sound waves making the sound unclear and often louder than the original source. To get a better idea of how sound and acoustics works, visit “Basic Behaviors of Acoustics”.
Sound travels through the air by vibrating the particles in the air. When sound hits a surface, that surface can either absorb some of the sound, reflect some of the sound or both. Every surface or object has different acoustical properties such as water transmits sound waves very well, wood vibrates and sends the sound waves through rooms and so on.
In the process of sound treatment, one would place sound absorption products on floors, walls, and ceilings in order to reduce the reverberation in a room and to reduce transfer of sound waves to other rooms. The keyword in the last sentence is reduce. All sound treatment products do not “soundproof” rooms, they only reduce sound travel where some products perform better than others. Fiberglass has been a preferred method of treating sound by absorbing as much of the sound waves as possible and reducing reverberation considerably. Recently, polyester products are becoming a standard to treat sound and although polyester products perform well, they are not as effective in sound absorption as fiberglass but this gap in deficiency is a narrow one. However, the reason polyester is becoming so popular is because it is easily made from recycled materials (post-consumer and post-industrial) as well as the end product being recyclable itself. Polyester is also much cleaner and easier to handle during manufacturing and installation and is much lighter in weight.
Soundproofing is a difficult task and involves skilled engineers and/or plenty of trial and error. To sound proof a room, you are basically blocking every avenue that sound has the ability to travel. This includes walls, ceilings, floors, door jambs, windows, window jambs, A/C duct, and more. This even includes electrical outlets. The materials used to absorb sound are helpful but to truly soundproof a room, you will need to use sound barriers that prevent sound travel or any vibrations caused by sound.