newbie: i'm so sorry, you all are probably tired of this

[artCROSS]

I did a lot of research on this forum and on the net, but i'm still as lost as ever. Why would you want to diffuse sound instead of absorbing it? Also...

Right now I record in a completely untreated room. It used to be a car hold, but the previous owners put up very thin walls and made it a room. Now it's where my band practices/records. I live w/ 4 other college students, and I'm renting, so I can't do any construction. Now for the vague question of the day: anyway to improve my situation? I'm not doing any of this for profit, and I'm going to move in a year or two, so I'm looking at DIY stuff. Example: putting extra carpet on the floor, putting bean bags in the room, stuff like that.

I read in Maxim Magazine (you know, that extremely reliable source for acoustic treatment) that putting egg cartons (gasp) on the ceiling will help the sound in the room. But of course, everyone disagrees. Will there be any noticeable difference in sound by doing this? Again, please remember I want to improve this situation with things around the house...when i move to my own place, that'll be a different story. Also, i read something about that pink insulation, but not sure how/where to use it.

Sorry for my ignorance, but I look foward to your help. Thanks

 

[RICK FITZPATRICK]

I did a lot of research on this forum and on the net, but i'm still as lost as ever. Why would you want to diffuse sound instead of absorbing it? Also...

First my disclaimer. I am not an expert in acoustics, butI'll try to put it in simple terms,
There are many reasons, but mainly because specular reflection(flat panel reflection) decays at beat intervals associated with the modal resonce of the room. That means the RT-60(reverberation decay time) varies with frequency. A diffuse soundfield has a uniform decay rate over many octaves. A specular reflection has about the same energy over time, as a direct sound, at an angle equal to incidence, although loss of energy via the inverse square law prevails. Diffused reflections exhibit a distribution of energy over a longer time frame and diffracted over a much wider angle.
Let me say something here though. Diffusion in a small room is considered difficult at best, impossible by some peoples opinion, and absolutely achievable over a certain frequency band if one reads The Master handbook of Acoustics by Alton Everest. Although other "experts" have led me to believe there exists a certain amount of ambiguity in regards to the meathods for achieving diffusion . Diffusion via absorption in patchs due to the "edge effect" has been demostrated somewhat, as is the total absorption coefficient of the room is improved if a given square footage of absorption material is distributed in patchs on the 4 walls and ceiling. Also, many manufactures of diffuser products will tell you that their products achieve broad band diffusion in small rooms, but others tell me the opposite.
So who do you believe? This subject has been a thorn in my continuing journey through the rabbit hole known as acoustics. Even now, I have questions posted on various acoustic and physics forums, to which some have been answered in ambiguous and carefully calculated response, which in some ways leave me absolutely baffled. I even had one so called "expert" respond to my reference of Everests book, as(my own words) " ...the first time I looked at this book I could hardly believe it was a book on acoustics". HUH? Go figure. In direct questions on a physics forums asking if the diffusers in the book do INDEED work, one acoustician said..."no doubt they do, but why build devices as shown from various material when patches of absorption material will produce the same results?..... Yet, various companys STILL sell tons of "patent pending" diffusers. ARRRRGGGGGGGGGRRRRRR

I've yet to hear ANYONE give a qualified YES or NO to whether diffusion CAN be achieved in a small room. PERIOD. So, I leave my limited quasi scientific non expert opinion at that.

Diffusion is a relatively newer subject of scientific investigation compared to absorption. And there are ONLY three things that can be applied to sound as far as acoustics are concerned. Reflection, absorption and diffusion. Each is a subject that could fill a book.
fitZ