In message <[email protected]>, dated Tue, 17 Jul 2007, Robert Johnson <[email protected]> writes:
>Of interest to you may be the IEC document 108/244/CD, part of the >proposed IEC 62368 hazard based standard likely to be published next >year. >It proposes limits of 118 dBA, up to 125 for handsets, 121 for inserted >earphones provided with the product, 136 for less than 0.5s, 130 under >fault conditions and 136 for less than 0.5s under fault conditions, >measured using parts of IEEE 269. There are also voltage limits for >audio sources. >Check with George Tsitsopoulos at your company for the complete text. This is about acoustic shock, high-level transients in telecomms terminals. It is a totally different subject from the subject of high programmes signal levels from portable players and exposure in clubs and the workplace. Unfortunately, people unfamiliar with this subject have indeed often confused them. It is NOT, as far as I know, controversial, although the 'traditional' (i.e. dating from the days of the General Post Office) UK limit was 126 dB SPL (not, IIRC, A-weighted, which is inappropriate at such levels anyway; the ear's response is nearly flat, so C-weighting would be more relevant). -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
