Just as with bump stocks, now that a suppressor has been used in one high profile crime, a move is afoot to ban the already highly regulated safety devices. Because any opportunity to roll back firearms freedoms for Americans will always be seized upon by the Civilian Disarmament Industrial Complex.
That’s why we thought it would be timely to run the official position paper on suppressor use that was issued by Doctors for Responsible Gun Ownership back in 2017, when the Hearing Protection Act still seemed like it might be a reality.
The causal relationship between loud noise exposure and irreversible hearing loss has long been recognized by medicine and the U.S. government. Chronic tinnitus (ringing in the ears) may accompany such permanent hearing loss.
Decades ago, the Occupational Safety and Health Administration (OSHA) defined noise levels that are risks to human hearing and standards to ameliorate them.3 These standards are soundly based on research on the effects of escalating sound levels on inner ear hair cell damage resulting in permanent hearing loss and tinnitus.
Cochlear Hair Cells and Noise Induced Hearing Loss
The National Institute on Deafness and Other Communicative Disorders (NIDCD) discusses cochlear hair cell damage in the inner ear that results in Noise Induced Hearing Loss (NIHL): 
A protein called gamma-actin helps repair mild to moderate ciliary damage, but cannot restore permanent damage from high-decibel noise such as from jet engines, loudly amplified music and, worse yet, explosive blast damage from gunfire. 
In this photomicrograph from a 1999 article Effects of Noise on Hearing in the Journal of the American Medical Association, intact and healthy sensory cells of the inner ear are shown on the left, and damaged cells from excessive noise exposure on the right: 
Explosive blast hearing damage
Particularly harmful for firearms enthusiasts is the explosive blast (or impulse) generated when firing a handgun or rifle. This explosive blast generates 1,000 times more pressure than the actual noise of a gunshot. Such blasts can result in significant, permanent hearing loss with a single exposure of 140 decibels or more, according to OSHA in the above referenced report.  This is the same “acoustic blast trauma” suffered by survivors of IEDs on the battlefield. Muzzle blast sound levels for most firearms (handguns, rifles and shotguns) range from 140 to over 170 decibels, more than sufficient to cause instant, permanent hearing damage.
An article from Military Medical Research in 2015 that discusses the etiology, pathology and impact of hearing loss from such powerful blast noise (particularly from munitions and aircraft) concludes: “Prevention is still the mainstay of treatment and soldiers need to be educated with regards to the use of hearing protection devices.”  According to the U.S. Department of Veterans Affairs: “Hearing loss, including tinnitus, which is a ringing, buzzing or other type of noise that originates in the head, is the most prevalent service-connected disability among Veterans, with many Veterans suffering from a form of it due to frequent exposure to loud noises from weaponry and aircraft.”  According to the Centers for Disease Control in Summary Health Statistics for U.S. Adults: National Health Interview Survey, 2012, “15% of adults aged 18 and over had some hearing trouble without a hearing aid,” which amounts to nearly 38 million Americans. [Emphases added.]
Auditory injuries sustained by bystanders are the same as for shooters. In fact, bystanders may not be prepared with any ear protection, and not anticipate the gunshot. Dr. Gianoli has “encountered several patients who had hearing loss from someone else shooting when they weren’t ready.”
Any intervention that reduces these morbidities, and certainly one that firearms users will gladly pay for themselves if it becomes affordable and readily available, could save billions of dollars in costly interventions. There is no treatment for this kind of hearing loss.
Hearing protection Hearing protection in the form of ear plugs or ear muffs, alone or in combination, can only reduce noise exposure by approximately 20-30 decibels. This limitation in noise reduction may still expose a firearms user to damaging levels of noise; 120 decibels is still louder than a car horn from three feet away. Thus, inside the canal and over the ear devices (i.e., ear plugs and ear muffs)—the only current generally available protection—are inadequate for impulse noise protection, and when used together they deafen the wearer to all external sound.
Research that demonstrates the superiority of suppressors over earplugs or earmuffs has been published by Matthew P. Branch, MD. In Comparison of Muzzle Suppression and Ear-Level Hearing Protection in Firearm Use (Otolaryngology-Head and Neck Surgery, 144(6) 950-953), he found that “All suppressors offered significantly greater noise reduction than ear-level protection, usually greater than 50% better. Noise reduction of all ear-level protectors is unable to reduce the impulse pressure below 140 dB for certain common firearms, an international standard for prevention of sensorineural hearing loss . . . Modern muzzle-level suppression is vastly superior to ear-level protection and the only available form of suppression capable of making certain sporting arms safe for hearing.”  [Emphasis added.]
Firearms suppressors, which have been popularly called “silencers”, do not make a weapon silent. That is Hollywood fiction. Commercially available firearms suppressors can alone reduce muzzle blast noise by around 30 decibels. Using a suppressor on a firearm concurrently with proper ear protection can reduce the amount of noise from shooting to safe levels safe for enthusiasts. Graphic from the Gun Owners Civil Rights Alliance in Minnesota: 
The Centers for Disease Control, in a September 2011 report titled Noise and Lead Exposures at an Outdoor Firing Range—California, documents the importance of hearing protection in shooting. It determined that noise levels above 160 decibels are routine at gun ranges and how even repeated exposure at lower decibel levels can be as damaging as fewer exposures at higher levels. It recommended “double protection” (i.e., earplugs and earmuffs used together) as the best currently available protection. But it noted that “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.”  [Emphases added.]
There is no effective treatment for hearing loss from high decibel acoustic blast noise. Maximal prevention is the only possible intervention. For shooters and bystanders, that begins with suppressors mounted on the firearms and may extend to supplemental use of earplugs and/or earmuffs.
But thanks to the 1934 National Firearms Act, gun suppressors are treated like machine guns. In states where they are allowed, they are still federally taxed and permitted, making their effective cost hundreds of dollars and requiring the applicant to wait at least 6 months before actually obtaining one. 
The contrast in strict U.S. regulation of suppressors to countries with stricter overall gun control like New Zealand and most of Europe where suppressors are entirely unregulated, effective and inexpensive is remarkable.
Concerns have been raised that minimizing restrictions to acquiring suppressors will result in increasing their use during commission of crimes and in greater difficulty identifying shots fired. But gunshots cannot be “silenced” below about 120 decibels. That is still very loud. Even the anti-gun Violence Policy Center in a February 2016 report claiming to document the dangers of suppressed gunfire, acknowledges its other advantages: greater barrel stability and less muzzle flip and recoil resulting in greater accuracy; enabling verbal communication among shooters (who needn’t be deafened by the noise or by their total ear protection); and eliminating muzzle flash, preserving night vision. 
Fearing the spread of criminal use of suppressors to conceal shootings is phobic, not reality-based. There are over 900,000 registered suppressors in America as of 2016.  In a 2007 paper, Paul Clark estimates that there are no more than 200 state and federal prosecutions each year for illegal silencer use.  That’s just a 0.02% rate.
Criminals prefer readily concealed firearms and are less concerned with the noise they produce. Homemade silencers can be made or other items repurposed very cheaply for single use, making the cost of buying a commercial suppressor even less attractive to criminals. And adding a commercial suppressor to a handgun typically doubles its length, making concealment much more difficult.
See illustration below:
In a January 2017 presentation just published online by The Laryngoscope, the authors concluded: “Substantial noise exposures with potentially serious long-term hearing health consequences frequently are occurring . . . with the use of firearms. Only a minority of those exposed consistently are using hearing protection. Healthcare providers should actively . . . encourage the use of hearing protection with those patients at risk.” 
Doctors for Responsible Gun Ownership strongly supports making firearm suppressors readily available to the public as a critical health intervention to prevent Americans’ hearing loss. Reducing barriers to firearms suppressor ownership and decreasing the likelihood of gunshot blast noise induced hearing loss and tinnitus in tens of millions of U.S. firearms owners will have no material impact on criminal firearms use.
1 H.R.367 – Hearing Protection Act of 2017
2 S.59 – Hearing Protection Act of 2017
3 OSHA Regulations (Standards – 29 CFR) – 1910.95(a)
4 NIDCD: Noise-Induced Hearing Loss
5 Gamma-actin is required for cytoskeletal maintenance but not development. BelyantevaI, Perrin B et al, Proc Natl Acad Sci USA, 2009 Jun 16;106(24):9703-8. 6 Effects of noise on hearing. ClarkeW & BohneB, JAMA, 1999;281(17):1658-1659. 7 Effect of Noise on hearing in the military. JongJ & WangD, Mil Med Res. 2015; 2:6.
8 National Audiology Awareness Month: Helping Veterans with hearing loss. VAntage Point: Official Blog of the U.S. Department of Veterans Affairs. October 5, 2016.
9 CDC: Summary Health Statistics for U.S. Adults: National Health Interview Survey, 2012. Vital and Health Statistics, Series 10, Number 260, February 2014.
10 Comparison of Muzzle Suppression and Ear-Level Hearing Protection in Firearm Use. BranchM, Otolaryngology-Head and Neck Surgery, 144(6) 950-953.
11 GOCRA Briefing: Sound Suppressors – Mufflers for Firearms. Gun Owners Civil Rights Alliance (Minnesota), March 2, 2015.
12 Noise and Lead Exposures at an Outdoor Firing Range─California. CDC Health Hazard Evaluation Report, ChenL & BrueckS, HETA 2011-0069-3140, September 2011.
13 Map: Suppressor Legality & Ownership. American Suppressor Association.
14 Silencers: A Threat to Public Safety. Violence Policy Center, February 2016.
15 Firearms Commerce in the United States: Annual Statistical Update 2016. United States Department of Justice—Bureau of Alcohol, Tobacco, Firearms and Explosives.
16 Criminal Use of Firearms Silencers. ClarkP, Western Criminology Review 8(2), 44–57 (2007).
17 Epidemiology of firearm and other noise exposures in the United States. BhattJ, LinH, BhattacharyyaN, The Laryngoscope online preview, March 16, 2017.