Help visualizing and understanding tangential standing waves

Post and discuss acoustic topics, Studio design, construction, and soundproofing here

Help visualizing and understanding tangential standing waves

Postby obieJon » Sat Apr 08, 2017 12:04 pm

Hi!

I understand how to calculate the frequencies of tangential standing waves using Rayleigh's equation but i'm confused about just about everything else on the topic.

In most textbooks the tangential standing wave is visualized as a ray tracing around a 2d space, hitting each wall once (in the case of 1 1 0 ). I'm not very strong in geometry, but isn't there an infinite amount of parallelograms you can fit into a rectangle? So how is there only a single 1 1 0? I understand that the sides of the parallelogram within the rectangle have to be integer multiples of each other... but surely there can be more than just one that satisfies the math.

And how does the fact that pressure maxima are always in the corners have to do with the ray tracing around (and never touching the corners).

I'm also confused by how the length/width of the sides of the standing wave parallelogram relate to the length/width of the sides of the room. In Rayleigh's equation we seem to be only plugging in numbers related to the room dimensions.

Anyone have a good animation of a tangential standing wave they can share?

Thanks for your time!
obieJon
 
Posts: 2
Joined: Fri Apr 07, 2017 5:20 pm

Re: Help visualizing and understanding tangential standing w

Postby bert stoltenborg » Mon Apr 10, 2017 9:48 am

You need symmetry.
If you shift the parallelogram you violate symmetry.
A standing wave is not a scalar but a vector creating a fixed, symmetric pattern in a room.

Antinodes are always in the corner, pressure flows to boundaries.

"I'm also confused by how the length/width of the sides of the standing wave parallelogram relate to the length/width of the sides of the room. In Rayleigh's equation we seem to be only plugging in numbers related to the room dimensions."
I'm not sure I understand your question.
If you view life with the knowledge that there are no problems, only opportunities, you are a marketing manager.......this is my personal philosophy
bert stoltenborg
 
Posts: 4566
Joined: Sun Apr 18, 2004 11:03 am
Location: Achterhood, Netherlands

Re: Help visualizing and understanding tangential standing w

Postby J.F.Oros » Wed Apr 12, 2017 12:42 pm

To expand a little on what Bert said about symmetry: because the angle of the reflected sound wave has to be equal with the angle of the incident wave, you will practically find only one solution for the parallelogram in that particular rectangle, which is a rhomboid (all sides of equal length), with its corners in the centers of the rectangle's sides.
... studiOTipper ...
J.F.Oros
 
Posts: 1868
Joined: Mon Feb 09, 2004 11:22 pm
Location: Romania

Re: Help visualizing and understanding tangential standing w

Postby bert stoltenborg » Wed Apr 12, 2017 9:29 pm

Flav,

Everything OK? We need to go OT, of course. :mrgreen:
If you view life with the knowledge that there are no problems, only opportunities, you are a marketing manager.......this is my personal philosophy
bert stoltenborg
 
Posts: 4566
Joined: Sun Apr 18, 2004 11:03 am
Location: Achterhood, Netherlands

Re: Help visualizing and understanding tangential standing w

Postby J.F.Oros » Fri Apr 28, 2017 12:58 pm

Ok Bert, lets do this! The thread starter doesn't seem to care much about people replying to him anyway :mrgreen:
... studiOTipper ...
J.F.Oros
 
Posts: 1868
Joined: Mon Feb 09, 2004 11:22 pm
Location: Romania

Re: Help visualizing and understanding tangential standing w

Postby bert stoltenborg » Sat Apr 29, 2017 12:34 pm

We're so awesome in explaining tech stuff that no questions remain :mrgreen:
If you view life with the knowledge that there are no problems, only opportunities, you are a marketing manager.......this is my personal philosophy
bert stoltenborg
 
Posts: 4566
Joined: Sun Apr 18, 2004 11:03 am
Location: Achterhood, Netherlands

Re: Help visualizing and understanding tangential standing w

Postby Yannick » Tue May 09, 2017 11:36 am

Couldn't one fill the room with different gasses ?

That should open up the room for OT responses :mrgreen:
Yannick
 
Posts: 130
Joined: Mon Nov 13, 2006 9:42 am
Location: Brussels


Return to Discussion

Who is online

Users browsing this forum: Bing [Bot], Google [Bot] and 1 guest

cron