Human Hearing And How To Lose It
By Will Dabbs, MD
Testosterone is the world’s most potent poison and age is no discriminator as regards its effects. My 78-year-old dad and his best friend were parked in the cab of his pickup truck at their hunting club, just soaking up the sunshine and enjoying some quality fellowship. That’s when the world’s third most brazen armadillo interrupted their reverie.
Deflated armadillos are so prevalent on Southern motorways they seem like they must be born dead on the side of the road. I am told these odd little creatures migrated north from Central America and were not found east of the Mississippi River until humans first bridged the waterway. History’s two boldest armadillos were clearly the first breeding pair to survive the bloody race across the bridge. Or perhaps the first example was pregnant. Regardless, this was at least one exceptionally brave armadillo. The one my dad encountered sauntered right up to the truck and began digging up his fresh deer feed plot.
Recognizing this as a capital offense, my dad produced his .22 Magnum revolver and loosed three rounds in quick succession. The armadillo leapt in the air as they are wont to do and raced for the nearby woodline at which point my dad’s pal emptied the 6-shooter out the opposite window. For our more sensitive readers, fret not. The armadillo escaped unscathed. My dad’s ears, however, were not so fortunate.
A lifetime’s exposure to gunfire and chainsaws had already taken their toll. Not unlike smoking, folks of my dad’s generation really didn’t know much about the deleterious effects of high-intensity noise exposure until the damage was done. In this case, my dad knew better but let his enthusiasm get the better of him. Now he rocks hearing aids. More on them later.
Auditory perception is the capacity to detect minute pressure changes transmitted through a transport medium, most typically air. Though most of us take it for granted, the whole affair is fairly miraculous if you think about it. Hearing is a form of mechanosensation wherein mechanical energy is translated into nerve impulses subsequently interpreted by the brain, predominantly in the temporal lobes. The outer ear includes the pinna, the part you can see, and this structure tends to focus sound into the ear canal and toward the eardrum or tympanic membrane. The outer ear helps us localize sound, and different animals sport different ear designs optimized for their needs.
Centerfire pistol cans very effectively muffle the sound of a gunshot but will remain unpleasantly loud unless
the can is charged with an ablative material and used with subsonic ammo.
The tympanic membrane vibrates ever so slightly in response to these pressure changes, and the ossicles transmit this energy to the inner ear for processing. These tiny bones, the smallest in the human body, consist of the malleus, incus, and stapes (the hammer, anvil, and stirrup for normal people). Within the inner ear resides the organ of Corti, an eponymous structure named after an Italian anatomist who died in 1876. The organ of Corti does the actual translation of mechanical energy into neuronal impulses via a fairly tedious though extraordinary process involving tiny hair cells. A pair of diminutive muscles within the ear tighten reflexively to help protect these sensitive structures when they are exposed to excessive noise. While hearing loss comes in a variety of flavors, the noise-induced sort most concerns us here.
Noise-Induced Hearing Loss (NIHL) can manifest as a steady decline in the capacity to hear over time resulting from chronic noise exposure. It can also manifest as a sudden and precipitous deficit resulting from exposure to a single loud noise like a gunshot. This abrupt event is called acoustic trauma. Such was the case with my dad. He did not hear well before touching off the pistol in the truck. Afterwards he was deaf as your proverbial post.
NIHL results from the overstimulation of the sensitive cells processing sound and, once lost, this hearing can’t be restored. NIHL also frequently manifests as a persistent ringing in the ears, something that drove my dad bonkers. The initial symptom is typically difficulty with conversation.
NIHL has two primary components. The first is a loss of audibility best visualized as a loss of volume. The second is frequency specific and is referred to as Signal-to-Noise-Ratio-Loss (SNR-Loss). Hearing aids can assist with the first sort but do little to help with the second. Consonants have a higher frequency than vowels in human speech and are typically lost first. The letters S and T are usually the first to go.
Textbooks have been written on the subject of hearing loss and we lack the space to do the subject justice here. Suffice to say the best way to treat NIHL is not to incur NIHL. Around 15 percent of teenagers suffer some degree of hearing loss because of the stupid things we all do as teenagers (loud music, concerts, sporting events). The number of American adults with NIHL is in the millions.
Modern hearing aids are extraordinary devices, but they still remain a sorry substitute for the original equipment. They are also expensive. My dad’s set him back just shy of $5 grand.
As with every aspect of modern life, today’s hearing aids are tied to your smart phone. Apps allow you to optimize the device for crowded rooms, restaurants, intimate conversations and similar predictable situations. Treble and bass are easily adjustable as is volume. Modern hearing aids feed inputs like music, cell phone calls and television audio directly into the device in the manner of ear buds. As you might imagine, this can be a great blessing for those with normal hearing who might otherwise also be watching television.
As with most everything else in life, the particulars of modern hearing aids are managed via a smart phone.
Modern hearing aids are unobtrusive and battery-powered. Dad’s batteries last about five days and are inexpensive. My dad’s units ride on the back of his ears and feed into his ear canal via a discrete wire. They represent the very definition of making the best of a bad situation. Those with sufficient NIHL to require hearing aids inevitably do a fair amount of subconscious lip reading, so it is beneficial to maintain a good line of sight while speaking.
If you are clutching this hallowed tome you have undoubtedly squeezed a trigger or three. Safeguard your hearing religiously. This means never discharge a firearm without hearing protection—period. A good friend keeps a pair of electronic muffs next to his defensive pistol in his bedside table. His tactical plan in the event of an intruder is to don the muffs as he secures his weapon. He tells me he hears better through them anyway. Another buddy literally lives with a pair of soft foam earplugs on a cord around his neck all the time he isn’t asleep or in the shower. This may seem silly, but they will be the ones laughing in a few years when all the rest of us are dropping five large ones on our own hearing aids. Heed their wisdom.
Electronic hearing protectors are readily available and are reasonably priced. They feature stereo amplification to help with sound localization and allow you to hear normal conversation while blocking out harmful noise even during active gunfire. Electronic Muffs can revolutionize your shooting experience.
Sound suppressors should be sold OTC in blister packs at WalMart. If sensible heads prevail we may yet see sound suppressors deregulated under a Trump presidency. It is a brave new world nowadays and anything is possible.
Sound suppressors reduce the sound of a gunshot, but do not truly silence it. Supersonic ammo and powerful guns can still produce dangerous levels of noise even with a quality sound suppressor in place. In my experience a nice .22-caliber suppressor can be hearing safe with the right gun and ammunition. Centerfire rifle cans running subsonic ammo are comically quiet. Most centerfire pistol suppressors need a little ablative material like water, Vaseline, shaving cream, or wire-pulling gel along with subsonic ammo to be truly hearing safe.
Using both earplugs and muffs is not a bad idea. A nice pair of electronic muffs is not expensive, while earplugs
cost literally pennies per pair. Leave a pair of these plugs in a deep pocket and let them get washed along with your
pants so they are always available. Caldwell Precision electronic hearing protectors allow you to hear and localize
speech while blocking high-intensity noise like gunshots.
A Perishable Commodity
You are only born with so much hearing capacity and once it is gone it never comes back. Blessed few of us will actually find ourselves humping the Hindu Kush stalking the Taliban so there is really no excuse for exposing your sensitive ears to the unfiltered ravages of gunfire. When I flew helicopters for Uncle Sam I always wore earplugs underneath my flight helmet. It took an extra moment before each mission and was kind of a hassle, but I can still hear fairly well.
Treat your hearing like the precious gift it is. Always use plugs, muffs, or preferably both when shooting and be actively vigilant about all high-intensity noise exposures. You can even use hearing protection to justify the purchase of a sound suppressor to a skeptical spouse. Explain you want to remain a pleasant conversationalist well into your sunset years. Who knows, it might just work.
Battenfield Technologies (Caldwell)
2501 Lemone Industrial Blvd
Columbia, MO 65201
Howard Leight, Honeywell Safety Products
900 Douglas Pike
Smithfield, RI 02917