ISEN-ASTC-L Archives

Informal Science Education Network

ISEN-ASTC-L@COMMUNITY.LSOFT.COM
Options: Use Forum View

Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
Re: whisper dishes
From:
William Katzman <[log in to unmask]>
Reply To:
Informal Science Education Network <[log in to unmask]>
Date:
Wed, 30 Jan 2013 07:39:39 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (125 lines) 
ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related institutions.
*****************************************************************************

Whisper dishes effectiveness vary based upon so many factors not the least of which is the size of the dish.  Since most people seem to talk into them (and not whisper) this increases their range.
Versions of them were used early on as a crude radar:  http://en.wikipedia.org/wiki/Acoustic_mirror

Essentially as the crude radar use goes it is like a parabolic microphone - gathering the sound that hits the dish and focusing it to one point.

In science centers the second dish can be used to make this more effective - essentially gathering the sound that would spread out everywhere and broadcasting it across in a straight line.  For this second use things in the way can be problematic - particularly if they are good sound absorbers (like humans or clay).

I'm guessing for the metal signage the sound could have either traveled around the sign as you suggested, or the receiving dish acted more like the early radar systems, OR the sound went through the signs - metal really is good at transmitting vibrations (which is what a sound is) without absorbing much of the energy.  Now try using signs made our of egg cartons, and i think you would have a different effect ;).

-William


On Jan 30, 2013, at 5:06 AM, Glen Moore wrote:

> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
> Incorporated, a worldwide network of science museums and related institutions.
> *****************************************************************************
> 
> We put our 5' dishes 40' apart - worked really well. Then we installed a temporary exhibition with metal signage panels directly between them I.e. removed the line of sight. They still worked almost as well! Presumably the sound travelled over the top of the panels and was then focussed. (?)
> 
> Sent from my iPhone
> 
> On 30/01/2013, at 2:37 PM, "Eric Siegel" <[log in to unmask]> wrote:
> 
>> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
>> Incorporated, a worldwide network of science museums and related institutions.
>> *****************************************************************************
>> 
>> hi, chuck,  you might get more responses if you change the title line.  We have whisper dishes that are probably 80 feet apart, and about 6 ft diameter.  but I don't have any general rules of thumb.
>> 
>> eric siegel
>> 
>> On Jan 29, 2013, at 5:04 PM, Chuck Howarth <[log in to unmask]> wrote:
>> 
>>> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
>>> Incorporated, a worldwide network of science museums and related institutions.
>>> *****************************************************************************
>>> 
>>> Hi, guys.  Does anyone know if there is an intrinsic limit on how far apart whisper dishes can be?  Would they work at a separation of 100 feet?  And if they are farther apart, does that mean that the dishes need to be bigger?  Many thanks, 
>>> 
>>> Chuck Howarth, Vice President
>>> ____________________________________
>>> 
>>> G Y R O S C O P E I N C
>>> 283 Fourth Street, Suite 201
>>> Oakland, CA 94607   
>>> 
>>> tele:   510.986.0111
>>> web:  www.gyroscopeinc.com
>>> blog:  http://museums-now.blogspot.com
>>> ____________________________________
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> ***********************************************************************
>>> For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org.
>>> 
>>> Check out the latest case studies and reviews on ExhibitFiles at www.exhibitfiles.org.
>>> 
>>> The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft. To learn more, visit
>>> http://www.lsoft.com/LISTSERV-powered.html.
>>> 
>>> To remove your e-mail address from the ISEN-ASTC-L list, send the
>>> message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
>>> [log in to unmask]
>> 
>> 
>> -- 
>> CONFIDENTIALITY NOTICE:
>> 
>> This message is intended solely for the addressee(s) in the first instance 
>> and may contain confidential information.  Please do not forward this email 
>> without the consent of the sender.
>> 
>> ***********************************************************************
>> For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org.
>> 
>> Check out the latest case studies and reviews on ExhibitFiles at www.exhibitfiles.org.
>> 
>> The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft. To learn more, visit
>> http://www.lsoft.com/LISTSERV-powered.html.
>> 
>> To remove your e-mail address from the ISEN-ASTC-L list, send the
>> message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
>> [log in to unmask]
> 
> ***********************************************************************
> For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org.
> 
> Check out the latest case studies and reviews on ExhibitFiles at www.exhibitfiles.org.
> 
> The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft. To learn more, visit
> http://www.lsoft.com/LISTSERV-powered.html.
> 
> To remove your e-mail address from the ISEN-ASTC-L list, send the
> message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
> [log in to unmask]

William Katzman
Program Leader
LIGO Science Education Center
"Inspiring Science"
[log in to unmask]
(225) 686-3134

***********************************************************************
For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org.

Check out the latest case studies and reviews on ExhibitFiles at www.exhibitfiles.org.

The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft. To learn more, visit
http://www.lsoft.com/LISTSERV-powered.html.

To remove your e-mail address from the ISEN-ASTC-L list, send the
message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
[log in to unmask]

ATOM RSS1 RSS2