Mark, You need to know what type of level you are working with. Sound power level (re 1pW) of multiple sources is straightforward: 10*log(n) = 13 dB for n=20. This is essentially independent of measurement environment. Sound pressure level (re 20uPa) depends on the sound power level plus the environment (measurement distance and room conditions). If you have a sound pressure level of a unit measured in free space conditions at a distance, the level due to multiple identical sources in the same environment will typically be no more than 10*log(n) because the distance to the acoustic centers of all sources will not be identical.
Lyle F. Luttrell, PE PeAk Storage Solutions, Div of MaxOptix 303-664-8286 fax 303-664-8299 lluttr...@peakstor.com From: Gandler, Mark [mailto:mgand...@ciena.com] Sent: Tuesday, January 21, 2003 4:31 PM To: emc-p...@majordomo.ieee.org Subject: Acoustic noise calculations for multiple shelves Hello Group! Imagine you are going to install 20 small chassis (shelves) in one rack in Central Office. If you know your acoustic noise level from one chassis, is it any way to calculate total noise? Sorry, if it is not the smartest question. Please reply!!! Need an answer!!! Thanks, Mark Gandler Ciena 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" 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"
