sound wave speed and other ways they behave/react.


I have this week free to play with acoustic treatments and more. I looking for more info, some type of reference if you will. It need not be a thousand pages long, something to guide me. Im planning to build more absorption and diffusers. That sort of reference would be helpful. Illustrations of frequencies and how they behave across the spectrum, there width and speed, that sort of thing. I have a room to work on and I’m starting with a clean canvass, 18L’ x 12’H x 7 1/2H.

All that exists is a cloth 3 seater sofa and an area rug that covers approximately 80% of the cork floor. I will leave an equal sized border at all four sides for now The walls are framed, all but one contain fibreglass pink. The option is there to add pink between the floor joists. As it is they are all open. I’m trying to stay away from a suspended ceiling. But sound before looks, I would rethink the covering.
meerzistar
Everest and pohlmann master handbook of acoustics. 

An experiment involving the speed of sound of acoustic waves: place three bowls of very cold tap water on the floor out in front of the speakers, with bowls arranged in a row left to right, one bowl located between the speakers. Listen to a familiar recording before and after placing the bowls of water on the floor. If you’re still not convinced remove the bowls and put them in another room (where they won't interfere) then listen again.



I agree with ohlala: (http://www.amazon.com/Master-Handbook-Acoustics-Sixth-Everest/dp/0071841040/ref=sr_1_1?ie=UTF8&q...)  Mine is the first edition, purchased in 1981.  I'm probably due for an update.
Regarding, " sound wave speed and other ways they behave/react".  If you want to focus on that aspect alone, copy/paste (Sabine reverberation) in your search bar and you'll get a plethora of helps. ie: (http://www.sengpielaudio.com/calculator-RT60.htm)
Geoff: your experiment designed to prove exactly what?
stevecham
2,251 posts
05-25-2016 7:14pm
"Geoff: your experiment designed to prove exactly what?"

It’s designed to illustrate how temperature of the air affects the speed of acoustic waves in the room. I.e., the acoustic waves nearer to the floor where the air is colder would be moving slower than the acoustic waves higher up in the room. Thus, the top of the acoustic wave would bend over the rest of the wave, like a wave coming into shore. And the listener would hear more of the sound.

Wouldn't the increase in humidity nearer the floor speed it back up? (Speed of sound is not just temperature dependent)
If you are going to investigate diffusers, take a look at AFMG Reflex software.  You can get a free month's use to demo (it expires after if you don't buy a licesnse, which would be expensive...but you can do a lot in a month).  Very informative to experiment with diffuser structures to see what they'll do.  Also, check out Tim Perry's website for some free design plans he made available
http://arqen.com/acoustics/acoustic-diffusers/
http://reflex.afmg.eu/
I also did my own design during the month I had to play with Reflex, thread at http://www.diyaudio.com/forums/multi-way/267682-diy-sound-diffusers.html
Great links thanks for those and the book issue.

Im putting one together modelling it after others Ive seen, with a few of my own tweaks added. I was thinking of a diffuser absorbtion dual treatment. Its only 2 feet by 4 feet though, some 10x10 windows with acoustic fiberglass hidden under burlap was an idea. They might not be large and effective enough deserving of the valuable surface area? Think I’m going against it and running angled and 90 degree boards end to end. With a cut out for the outlet. Its going to hide wires that must run 1 foot up the wall, another little bonus. Im using 6 species of wood very dark to very light and in between. the finish should have some WAF after a lot of sanding and Danish oil.
gs5556
589 posts
05-25-2016 11:12pm
"Wouldn't the increase in humidity nearer the floor speed it back up? (Speed of sound is not just temperature dependent)"

good point.  The speed of sound is much more sensitive to temperature than to humidity. So the answer to your question is no.

cheers