Ahhh! Guilty! Thanks Ken. >From my posting below, the part about "3dB for each shelf" is WRONG!!!!!!. Hopefully, I didn't corrupt any innocent minds. It would be more correct to say 3dB for each factor of two, 1 to 2, 2 to 4... I'm glad that I wasn't designing any airplanes today!
SNIP >>For sound, the worst case would be to add 3dB for each shelf. However, in the real world, the >>noise probably won't all add together (there will be power/phase/frequency differences). SNIP Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | > -----Original Message----- > From: Ken Javor [SMTP:ken.ja...@emccompliance.com] > Sent: Wednesday, January 22, 2003 12:56 PM > To: Luttrell, Lyle; 'Gandler, Mark'; emc-p...@majordomo.ieee.org > Subject: Re: Acoustic noise calculations for multiple shelves > > > I would further amplify on this comment. It is not just a 10 log vs. 20 log > calculation. Sound power is the quantity of interest, so by definition it > is a 10 log relationship . But someone said add 3 dB for each added > component. That is incorrect. You only add 3 dB for the second component. > The issue is that the sound pressure level (exclusive of localized > interference effects) adds as the square root of the sum of the squares. > And that is what you get when you use 10 log(number of units). > > > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
