Quite right for uncorrelated noise. To add to this discussing we can think about the response of the human ear to sound level. A 3 dB increase in SPL does not sound twice as loud. If I remember correctly it takes a 6-8 dB increase to "sound" twice as loud. So is the goal to meet a standard or for operator comfort?
Dave Cuthbert Micron Tech From: Ken Javor [mailto:[email protected]] Sent: Wednesday, January 22, 2003 10:56 AM To: Luttrell, Lyle; 'Gandler, Mark'; [email protected] 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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"
