Since I’m in our colo facility this morning, I decided to put some numbers on it in my little isolated corner with lots of blowers running. According to my iPhone SPL meter, average SPL is 81 - 82 dB with peaks 88 - 89 dB. According to the OSHA hearing protection chart, 90 dB is the maximum level for 8-hour daily exposure. See https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9735 Etymotic, a manufacturer of high performance ear buds/ear phones says 85 dB is acceptable 8 hours per day, 5 days per week. See http://www.etymotic.com/downloads/dl/file/id/15/product/82/guide_to_safe_lis... There is some argument to the point of what type of noise but ~10 dB is still pretty good headroom using the OSHA limits and 4 dB is certainly usable for the Etymotic figure. In the general area the levels are 6 - 9 dB lower. My thought is if you’re listening to music many hours per day you’re may be exceeding these levels already. On Sep 23, 2015, at 8:48 AM, Bryan Holloway <bholloway@pavlovmedia.com<mailto:bholloway@pavlovmedia.com>> wrote: On 9/23/15, 7:53 AM, "NANOG on behalf of Joe Greco" <nanog-bounces@nanog.org<mailto:nanog-bounces@nanog.org> on behalf of jgreco@ns.sol.net<mailto:jgreco@ns.sol.net>> wrote: Maybe I've always listened to my music to loud and spend the bulk of time via ssh, but I've never felt a need for hearing protection in a DC, is this generally an issue for people? Depends on how long and how noisy. As I've gotten older, I find loud noise in general is less tolerable, so I've taken to always keeping a pair of earplugs with me. It makes being around loud music, etc., much more enjoyable. Long term exposure to noise is widely considered to be a hazard, but walking into an average data center for an hour once a month is probably not that risky. ... JG Depends on the type of "noise" too. Datacenters generate (more or less) white noise, which is particularly harmful long-term to the cilia in your ears because it excites all of them all of the time. A loud datacenter is much worse than a loud rock band, IMO. I personally use Bose noise-canceling headphones. --- Keith Stokes