John Sayers' Design Forum

John Sayers' Recording Studio Design Forum

A World of Experience
Click Here for Information on John's Services
It is currently Wed Dec 11, 2019 8:05 am

All times are UTC + 10 hours




Post new topic Reply to topic  [ 25 posts ]  Go to page Previous  1, 2
Author Message
 Post subject:
PostPosted: Tue May 16, 2006 6:36 am 
Offline
User avatar

Joined: Sat Jan 01, 2005 3:06 am
Posts: 92
Location: Michigan
Brilliant animation! That's exactly what I was looking for. It really helps to visualize this. I see they have a whole teaching section too, linked at the home page.

http://www.isvr.soton.ac.uk/SPCG/

I'm busy reading the print outs now from several sites and the ones you mentioned. I'll be back with a better understanding or maybe new questions. Thanks again.


Report this post
Top
 Profile  
 
 Post subject:
PostPosted: Tue May 16, 2006 11:35 am 
Offline
Senior Member
User avatar

Joined: Sun Mar 16, 2003 11:11 am
Posts: 6978
Location: West Coast, USA
So much good stuff in here (thanks David, Andre, and Lex for asking :=) I've made it a "sticky" so it won't get buried... Steve

_________________
Soooo, when a Musician dies, do they hear the white noise at the end of the tunnel??!? Hmmmm...


Report this post
Top
 Profile  
 
 Post subject:
PostPosted: Wed May 17, 2006 4:01 am 
Offline
User avatar

Joined: Sat Jan 01, 2005 3:06 am
Posts: 92
Location: Michigan
Good idea Steve. I agree, this has turned into a great learning thread.

http://www.isvr.soton.ac.uk/SPCG/Tutori ... quency.htm

I looked at the bottom animation and was confused for a while. I was wondering about how that was possible without changing the pitch. But then pitch is dependent on the frequency. Then I thought how the velocity could only change if the medium changed or the conditions of the air changed. If this happened, then all waves would adjust and would still have the same frequency. I think I understand it now.

So the bottom animation is really an example of the same frequency moving through two different mediums.


Report this post
Top
 Profile  
 
 Post subject:
PostPosted: Thu May 18, 2006 11:14 am 
Offline
User avatar

Joined: Sat Jan 01, 2005 3:06 am
Posts: 92
Location: Michigan
Quote:
The correctable frequency range for both “peak” and “dip” correction spans from 20 Hz -250 Hz. The upper limit of 250 Hz was picked because of its wavelength. (The wavelengths at 20 Hz and 250 Hz are 56.5 feet and 4.5 feet respectively.) According to Jim Muller, above 250 Hz the wavelengths become so short that room resonance modes merge together to be indistinguishable. The short wavelength would also require a different correction from seat to seat. If you were to correct for frequencies that are in the 5 kHz - 10 kHz region, the wavelength is so short (on the order of inches) that even head movement in a given seat would yield response fluctuations! Frequencies above 250 Hz are best dealt with through the use of acoustic absorption materials like foam or fiberglass. V4 wisely leaves this range untouched.


Found this quote here:
http://www.hometheaterhifi.com/volume_1 ... -2004.html


Report this post
Top
 Profile  
 
 Post subject: Question for a Physicist
PostPosted: Sun May 21, 2006 3:06 am 
Offline
User avatar

Joined: Sat Jan 01, 2005 3:06 am
Posts: 92
Location: Michigan
This one is definitely a theory question for the physicist acoustician if you would be kind to enlighten me :idea: or give me directions. :)

After reading and observing about sound basics (frequency, velocity, wavelength, compressions, rarefactions, rays, waves, amplitude, intensity), and its behavior in different circumstances (diffraction, diffusion, reflection, refraction, interference), I am left with some fundamental questions.

Quote:
In distant rooms the bass notes are more prominent because their longer wavelengths are readily diffracted around corners and obstacles.
(pg 245 Master Handbook of Acoustics)

Ok, we are all familiar with this type of phrase but I'm wondering, why? I know after reading this excellent book that sound at different frequencies behaves differently depending on which range it falls. (pg 324 of the Master Handbook of Acoustics is excellent)

Here are a couple of paragraphs from Everest on these differences:

(pg 236 Master Handbook of Acoustics)
Quote:
Below 300-400 Hz, sound is best considered as waves (chapter 15 expounds on this). Sound above 300-400 Hz is best considered as traveling in rays. A ray of sound may undergo many reflections as it bounces around a room. The energy lost at each reflection results in the eventual demise of that ray. Even the ray concept is an oversimplification: Each ray should really be considered as a "pencil" of diverging sound with a spherical wavefront to which the inverse square law applies.

The mid/high audible frequencies have been called the specular frequencies because sound in this range acts like light rays on a mirror. Sound follows the same rule as light. The angle of incidence is equal to the angle of reflection, as in Fig. 10-2.


Why do the high frequencies act as rays and why do the low frequencies act as waves? The frequency only determines the amount of wavefronts or compressions per unit of time but the wavefronts are the same(originate at a source and spread out in spherical fashion) for any sound. So why is it the wavefronts of low sounds can go around objects while the wavefronts of high sounds are reflected? Is this a difference of energy that it comes down to? The wavelengths are afterall the distance between the compressions or rarefactions and not a measurement of the wideness of a wave. The wavefront is not linear and finite, it is curved and infinite. So why is the wavelength which strikes perpendicular to the object the determinant of why a wave can go around an object?

Can someone help me understand this or tell me where I can find this information because I have been reading and not finding anything except general explanations? Thanks.


Report this post
Top
 Profile  
 
 Post subject:
PostPosted: Sun May 21, 2006 9:35 pm 
Offline
Senior Member
User avatar

Joined: Wed Jun 18, 2003 6:09 pm
Posts: 760
Location: Antwerp/Belgium
For info to others.

You also entered the same here, where some responses followed:
http://forum.studiotips.com/viewtopic.php?t=2301

_________________
Best regards - Eric Desart
My posts are never meant to sell whatever incl. myself, neither direct, nor indirect.


Report this post
Top
 Profile  
 
 Post subject:
PostPosted: Mon May 22, 2006 6:26 am 
Offline
Senior Member
User avatar

Joined: Wed Jun 18, 2003 6:09 pm
Posts: 760
Location: Antwerp/Belgium
This one is good in 3D

http://web.archive.org/web/200108092000 ... terOne.asp

:twisted: I always loose this link. Since it's a sticky I at least know where to find it back. Bob Golds originally found this one.

_________________
Best regards - Eric Desart
My posts are never meant to sell whatever incl. myself, neither direct, nor indirect.


Report this post
Top
 Profile  
 
 Post subject:
PostPosted: Mon May 22, 2006 7:45 am 
Offline
Senior Member
User avatar

Joined: Sun Mar 16, 2003 11:11 am
Posts: 6978
Location: West Coast, USA
Thanks for posting that, as well as the studiotips thread Eric; now we BOTH can find 'em 8) Steve

_________________
Soooo, when a Musician dies, do they hear the white noise at the end of the tunnel??!? Hmmmm...


Report this post
Top
 Profile  
 
 Post subject:
PostPosted: Wed May 24, 2006 6:41 am 
Offline
User avatar

Joined: Sat Jan 01, 2005 3:06 am
Posts: 92
Location: Michigan
Thanks Eric, I was going to do that but you beat me to it. :wink:


Report this post
Top
 Profile  
 
 Post subject:
PostPosted: Sat Sep 27, 2008 11:55 am 
Offline

Joined: Fri Sep 26, 2008 1:47 am
Posts: 13
Location: Western Massachusetts USA
David French wrote:
This is the closest thing I've seen.

http://www.hunecke.de/english/calculato ... modes.html

quick question: in that calculator: the "Distribution of Frequencies" graph, the blue bars represnt: the frequncies that will be 'dead' or 'too loud' in the room?

and the 'room box': what do black or white colors represent?


Report this post
Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 25 posts ]  Go to page Previous  1, 2

All times are UTC + 10 hours


Who is online

Users browsing this forum: No registered users and 10 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group