Re: Shape of background noise ("Kevin O'Connor" )

Subject: Re: Shape of background noise
From:    "Kevin O'Connor"  <knoconnor@xxxxxxxx>
Date:    Tue, 22 May 2007 13:22:04 -0700

<html> <body> <font size=3D3><br> Maybe so.&nbsp; But so-called =93Hoth noise=94(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).&nbsp; <br> &nbsp;<br> Despite the fact that Hoth=91s measurements were made in several acoustic environments - office buildings, stores and residences in Philadelphia and NYC =96 the power spectra, surprisingly, displayed much the same form, differing primarily in overall level.&nbsp; His average spectrum plot (Fig. 7) is nearly linear (dB x log F) falling a rate of ~5-6 dB/oct.&nbsp; <br> &nbsp;<br> 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.<br><br> Kevin<br><br> Kevin O'Connor<br> Center for Neuroscience and <br> Section of Neurobiology, Physiology and Behavior<br> UC Davis<br> Davis, CA&nbsp; 95616<br> (530) 752-5304<br> knoconnor@xxxxxxxx <br><br> <br> At 06:33 PM 5/21/2007, Ralph Muehleisen wrote:<br> <blockquote type=3Dcite class=3Dcite cite=3D"">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.&nbsp; I believe that changes in building construction and building systems along changes in outdoor environmental noises make such a dated study inappropriate.&nbsp; I would suggest that you avoid references before the mid 80's.&nbsp; <br><br> Ralph<br><br> -- <br> Ralph T. Muehleisen<br> Assistant Professor, Civil and Architectural Engineering<br> Illinois Institute of Technology, Chicago, IL 60616<br> tel: 312-567-3545&nbsp;&nbsp;&nbsp; fax: 312-567-3519<br> email: <a href=3D"mailto:muehleisen@xxxxxxxx">muehleisen@xxxxxxxx</a>&nbsp;&nbsp;&nbs= p; url:<a href=3D""> /muehleisen</a> <br><br> On 5/21/07, <b>Kevin O'Connor</b> &lt;<a href=3D"mailto:knoconnor@xxxxxxxx">knoconnor@xxxxxxxx</a></font= >&gt; wrote:<br> <dl><br> <dd>Also:<br> <dd>Hoth, DF.&nbsp; Room noise spectra at subscribers' telephone locations.&nbsp; J. Acoust. Soc. Am., 12:&nbsp; 499-504, 1941.<br><br> <dd>Kevin<br><br> <br> <dd>Kevin O'Connor<br> <dd>Center for Neuroscience and <br> <dd>Section of Neurobiology, Physiology and Behavior<br> <dd>UC Davis<br> <dd>Davis, CA&nbsp; 95616<br> <dd>(530) 752-5304<br> <dd><a href=3D"mailto:knoconnor@xxxxxxxx">knoconnor@xxxxxxxx</a> <br><br> <br> <dd>At 01:23 PM 5/21/2007, Brian Gygi wrote:<br> <blockquote type=3Dcite class=3Dcite cite=3D""> <dd>&nbsp;<a= href=3D"mailto:AUDITORY@xxxxxxxx">AUDITORY@xxxxxxxx</a>= </blockquote><br> </dl></blockquote></body> <br> </html>

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