Hi Paul, Sound pressure level (SPL) is normally given for sustained or peak levels for different environments. The dB(A) unit for SPL is relative to the threshold of hearing. The "A" in the dB(A) indicates the measurement is taken with an A-weighted filter which shapes the frequency response in a prescribed manner.
Sound pressure level above "ambient" would be quite a different concept. For instance, room conversation is roughly 60dB(A). To get 80dB above that ambient, you'll end up with 140 dB(A)!This would be extremely loud and unsafe in my estimate. --------------------------------------------------------------------- Dan Kwok, P.Eng. Principal Engineer Electromagnetic Compatibility Intetron Consulting, Inc. Ph (604) 432-9874 E-mail [email protected] Internet http://www.intetron.com ----- Original Message ----- From: <[email protected]> To: "SEHS Grapevine" <[email protected]>; <[email protected]> Sent: Friday, October 19, 2001 6:56 AM Subject: Re: What is minimum dBA measured difference above ambient noise for pulsing alarm. > > > Folks, > > Can anyone cite a reference document / standard that determines if there is > a minimum dBA sound level variation above an expected ambient environment > that is suitable for a pulsing alarm. > > In my review , I have found that SEMI S2-0200E Environmental, Health, and > Safety Guideline > for Semiconductor Manufacturing Equipment states in Para. 27.1 ".......Equipment should be designed to > control exposures to sound pressure levels equal to or greater than sound pressure levels equal to or greater > than 80 dBA continuous or intermittent sound pressure level, and 120 dB instantaneous (impulse) sound pressure level." > > Further, 29 CFR 1910.95 " Occupational noise exposure" states " > ........... 2.) If the variations in noise level involve maxima at > intervals of 1 second or less, it is to be considered continuous. " Are > there any industry standards that recommends a pulse level variation? > > Your input on this subject is greatly appreciated. > > Best Regards, Paul J Smith > Teradyne, Inc., > Boston, MA 02111 > [email protected] > Voice 617-422-2997 > Fax 603-843-7526 > > > > > ------------------------------------------- > 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: > Michael Garretson: [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: > No longer online until our new server is brought online and the old messages are imported into the new server. > ------------------------------------------- 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: Michael Garretson: [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: No longer online until our new server is brought online and the old messages are imported into the new server.
