Here are some links I have found. The one about hunting dogs is relevant to the discussion.
With many rifles, especially rifles with shorter barrels, like the "pistols" that shoot rifle rounds, rifles with muzzle brakes, and higher than average velocity rifles, it is impossible to get to safe sound levels if you don't use a suppressor in addition to other hearing protection.
######### Hearing Loss Studies & Statistics ###########
http://www.atf.gov/sites/default/files/ ... t_2014.pdf
http://www.asha.org/public/hearing/Recr ... -Exposure/
http://hearinghealthfoundation.org/statistics statistics of hearingloss
http://www.betterhearing.org/hearingped ... aring-loss
http://www.betterhearing.org/
--- Hunters / Men ---
http://triggered.clockss.org/ServeConte ... ll/9/4/352 ...recreational firearms is associated with marked high-frequency hearing loss in men.
http://www.nidcd.nih.gov/health/inside/ ... s/pg2.aspx Hunters often don't wear protection, but should.
--- Children ---
http://c.ymcdn.com/sites/www.hearingcon ... ngv1.4.pdf
http://informahealthcare.com/doi/abs/10 ... 013.865845 exact same as above, but it's the primary source.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2532893/ Noise-induced hearing loss in children
http://www.entnet.org/content/noise-ind ... s-children
http://www.livestrong.com/article/52853 ... r-infants/
--- Dogs ---
http://www.msstate.edu/web/media/detail.php?id=1812 Hearing loss in hunting dogs. "Practically all of the hunting dogs have some hearing loss and practically all of the non-hunting dogs have great hearing." The difference in hearing ability between the two test groups "is extreme," he added.
######### physics of Noise ##########
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA468459 .mil covers sound pressure, and bone conduction.
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA454471 .mil NIHL, read section 15-2. NIHL, section 15-2. "...limit ... muffs and/or plugs, because they do not attenuate sounds that are conducted to the inner ear by the hard and soft tissues of the head and body."
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA501586 .mil nice graphs, plugs can't help you by themselves
http://home.earthlink.net/~dnitzer/4Haa ... cibel.html a chart with decibel levels, not great.
http://www.coopersafety.com/noisereduction.aspx
http://www.silencerresearch.com/hearing_protection.htm value of plugs, degree of suppressor reduction
http://www.earplugstore.com/morabshootea.html
36 dB (C-weighted) is the maximum possible using ear muffs and ear plugs simultaneously, equating to only a 36 - 7 = 29 dB(A) protection.
http://www.ncbi.nlm.nih.gov/pubmed/7761796 characteristics of gunfire
http://www.audiologyonline.com/releases ... aring-4302
http://acoustics.org/pressroom/httpdocs ... 3pNS3.html acoustic helmet
https://www.sbir.gov/sbirsearch/detail/264669 Advanced Helmet for Maintainer Head and Hearing Protection
https://www.youtube.com/watch?v=9zTXiPcpLV0&t=195 HowStuffWorks - can sound kill you?
######### Regulations #############
http://www.msha.gov/regs/complian/guide ... ide303.htm mining regs, refers to when dual protection is required.
https://www.osha.gov/dts/osta/otm/noise ... ation.html
https://www.osha.gov/dts/osta/otm/new_noise/ Very long, 140db max for firearms before hearingloss.
http://wp.roedale.de/en/hauptmenue/schi ... erschaden/ Some Facts and Government regulations from across the pond
http://www.cdc.gov/niosh/docs/wp-soluti ... 13-104.pdf If state law permits, consider providing noise suppressors for gun barrels
http://www.cdc.gov/niosh/hhe/reports/pd ... 9-3140.pdf The only potentially effective noise control method to reduce students’ or instructors’ noise exposure from gunfire is through the use of noise suppressors that can be attached to the end of the gun barrel. However, some states do not permit civilians to use suppressors on firearms.
http://www.cdc.gov/niosh/hhe/reports/pd ... 4-3208.pdf What the Employer Can Do... Use noise suppressors on firearms, if feasible.
We recommended using dual hearing protection during all live fire training exercises and installing additional noise controls.
https://www.osha.gov/dts/osta/otm/new_noise/
######### Opinion - Editorial ###########
http://www.dailykos.com/story/2007/11/0 ... -to-obtain
######### Industry ##########
http://www.silencertalk.com/results.htm suppressor noise measurements
http://www.nssf.org/factsheets/PDF/Suppressors.pdf
http://www.nssf.org/factsheets/
http://www.gunfacts.info/infographics/
http://acoustics.org/pressroom/httpdocs ... 3pNS3.html acoustic helmet
######### Suppressors 2015 #########
######### MN Legislative Links and Video #########
http://www.house.leg.state.mn.us/htv/ar ... ls_year=89 House Public Safety and Crime Prevention Policy and Finance Committee
https://events.qwikcast.tv/QwikCast/Qwi ... ageId=1366 Minnesota House Live Webcast and Mobile Stream
http://www.house.leg.state.mn.us/htv/pr ... _id=881927 TV feed