17 November 2020

Soundproof vs Acoustic treatment, is it the same?

This is a very common question, many will says that it is very easy to sound proof a wall, just add acoustic foam to cover the whole walls and that it. My friend, doing this does not make your room sound proof or the wall soundproof. all it does it, it just modify the sound reflect onto the wall i.e. it absorbed the sound. Acoustic foam is usually used for acoustic treatment.  Acoustic treatment is a method to control the echoes and reverberations inside the room. Whereas soundproof is about isolating the room from outside noise coming into or noise from inside going out of the room.   

Let us discuss some basic acoustic for us to get an idea and a better understanding of these confusing subject.

    Extracted from: https://auralex.com/alpha-dst-roominator-kit/

Acoustic treatment:

(the following statement is extracted from Acoustic 101(Auralex) by Eric T. Smith, page 6, 7 . 2014).

    One of the single biggest concepts to understand and appreciate is that (Auralex) acoustic foam, one of our core products, is not going to "soundproof" your room. It is an extremely effective absorber of ambient, reflected sound and helps make rooms "sound better." Acoustic foam does contribute some sound isolating properties (mostly high frequencies), but is not sufficient by itself to keep sound in or out of a room. 

    Thicker acoustic foam is better at absorbing low frequency sounds. Controlling reflected sound within a room is extremely important in producing good sounding recordings. 

Image extracted from : https://all.biz/tr-en/bondex-30mm-g278659

Sound Proof:

(the following statement is extracted from Acoustic 101(Auralex) by Eric T. Smith, page 6 . 2014).

• When sound strikes a surface, some of it is absorbed, some of it is reflected and some of it is transmitted through the surface. Dense surfaces, for the most part, will isolate sound well, but reflect sound back into the room. Porous surfaces, for the most part, will absorb sound well, but will not isolate.

• The best way to stop sound transmission through a building structure is to isolate the sound source from the structure before the structure has a chance to vibrate.

• Walls need to be isolated from ceilings and floors, usually by means of dense, pliable rubber.

• The main ways to minimize sound transmission from one space to another are adding mass and decoupling.

• Limp mass is most often better than rigid mass (actually, a combination of the two is really what you are after).

• Every object, every construction material has a resonant frequency at which it is virtually an open window to sound — kind of like a tuning fork that “sings” at its particular resonant frequency.

• Different materials have different resonant frequencies.

• Trapped air (a.k.a., air spaces and air gaps) is a very good decoupler.

• Airtight construction is a key concept. Sound, like air and water, will get through any small gap. (Sound can leak through openings as small as 1/32” – in some cases even smaller.)

• Sound bounces back and forth between hard, parallel surfaces.

Soundproofing is not an easy Job and it is recommended to refer the job to professional team or acoustic consultant who has experience building soundproof structure. It should by no mean attempted by DIY or laymen as there are many areas if not done properly can cause sound to leak through gaps or flanking path or faulty structure which may cost more to amend then to build. In addition, there are measurement (acoustic report) need to be carried out before and after the job is done. 

Reference :

Acoustic 101, Practical Guidelines For Constructing Accurate Acoustical Spaces by Eric T. Smith Edited by Jeff D. Szymanski, PE July 2004 Version 3.0