Re: Shape of background noise

["Kevin O'Connor" <knoconnor@xxxxxxxxxxx>]

Maybe so.  But so-called ?Hoth noise?(based on his 1941 paper) is
evidently still used as an IEEE standard (269-2001) for ambient room
noise for the evaluation of analog and digital communication equipment
(based on a fast Google search).  
 
Despite the fact that Hoth?s measurements were made in several acoustic
environments - office buildings, stores and residences in Philadelphia
and NYC ? the power spectra, surprisingly, displayed much the same form,
differing primarily in overall level.  His average spectrum plot
(Fig. 7) is nearly linear (dB x log F) falling a rate of ~5-6
dB/oct.  
 
Ralph may be right - that modern building design and materials may have
significantly changed our synthetic acoustic environments, and it is
certainly an interesting empirical question with implications for a
standard that has been on the books for a long time.

Kevin

Kevin O'Connor
Center for Neuroscience and 
Section of Neurobiology, Physiology and Behavior
UC Davis
Davis, CA  95616
(530) 752-5304
knoconnor@xxxxxxxxxxx 


At 06:33 PM 5/21/2007, Ralph Muehleisen wrote:

While useful for studying the changes in background noise over the last 65 years, the last reference is probably not applicable to characterization of nearly any modern built environment.  I believe that changes in building construction and building systems along changes in outdoor environmental noises make such a dated study inappropriate.  I would suggest that you avoid references before the mid 80's. 

Ralph

--
Ralph T. Muehleisen
Assistant Professor, Civil and Architectural Engineering
Illinois Institute of Technology, Chicago, IL 60616
tel: 312-567-3545    fax: 312-567-3519
email: muehleisen@xxxxxxx    url:http://acoustics.iit.edu/muehleisen

On 5/21/07, Kevin O'Connor <knoconnor@xxxxxxxxxxx> wrote:

Also:

Hoth, DF.  Room noise spectra at subscribers' telephone locations.  J. Acoust. Soc. Am., 12:  499-504, 1941.

Kevin

Kevin O'Connor

Center for Neuroscience and

Section of Neurobiology, Physiology and Behavior

UC Davis

Davis, CA  95616

(530) 752-5304

knoconnor@xxxxxxxxxxx

At 01:23 PM 5/21/2007, Brian Gygi wrote:

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