Life Extension Magazine May 2012
Strategies to Protect and Preserve Your Hearing
By Alexander Brookner
So much of what we term “science” emanates from real-world experiences.
In my case, I was recently exposed to loud noise that resulted in me developing acute tinnitus that has not fully gone away. I am compelled to relate this incident to spare others the same fate.
About six months ago, a group of doctors were in South Florida attending a medical conference. I was invited to go out with them to dinner and they asked me afterwards to join them at a nightclub.
When we entered the nightclub, the music was rather subdued and I was able to engage in good scientific discussions with these doctors over drinks. As the night wore on the music was slowly “cranked up.” We nonetheless continued our discussions by talking louder.
During the last hour, the music decibels increased so much that one of the doctors had to scream in my ear to be heard. If I had to do it over, I would have walked out.
The next day I woke up with severe tinnitus. When I did a Google search to see if one incident of loud noise could cause permanent ringing in the ears I was surprised as to how many people develop tinnitus because of one exposure to loud noise.
In my case, it was not just the doctor screaming in my ear over very loud music. When one ingests ethanol, the tiny bones in the ear lose their ability to close in response to loud sounds. Aging also plays a role in our vulnerability to ear damage caused by loud noises.
So because of this one confluence of mishaps, I am left with mild tinnitus. To sleep, I turn up my air purifier so it covers up the ringing. I do this sometimes in the daytime also. For the most part I just try to ignore it.
One major change I made is to carry ear plugs with me whenever I may be exposed to any kinds of excess noise. Putting in these ear plugs enables me to hear conversation, but drastically reduces the background noise that enters my ears.
So the take-home lesson I want to relay to Life Extension® members is:
The following article discusses partial solutions for mitigating tinnitus.
Strategies to Protect and Preserve Your Hearing
According to the Environmental Protection Agency, noise pollution “adversely affects the lives of millions of people.”1 The EPA warns that health problems related to noise can include high blood pressure, sleep disruption, stress related illnesses along with countless other adverse health issues.2 Noise Induced Hearing Loss (NIHL) is the most recognized damaging impact of loud noise. Part of the reason that noise pollution has not received the critical public attention of air or water pollution is because you cannot see it or taste it. Yet, if you are one of the 10 million American adults who experiences noise-induced hearing loss, or one of the 40 million with chronic tinnitus (ringing in the ears), you already understand the stressful impact of noise on your life.3,4 What most doctors and audiologists don’t tell you is what you can do to help restore some of your lost function, and prevent further damage. In this article, we will provide specific steps you can take to shield yourself and your family from the growing dangers of chronic noise.
Long-Term Health Risks of Noise Pollution
Experts estimate that 30 million Americans are exposed to dangerous levels of noise each day.5
Chronic loss of hearing, especially in the higher frequencies where we perceive speech, is becoming increasingly common, with 10 million adults and 5.2 million children suffering from irreversible noise-induced hearing loss in the US alone.4 Frighteningly, people are developing measurable hearing loss at earlier and earlier ages.6
Tinnitus, the most common auditory disorder, affected about 40 million people in the US in 2010.3 There’s no medical cure for tinnitus, and its incidence is rising, chiefly due to noise in the environment.3
While progressive hearing loss and tinnitus have obvious impact on your quality of life, there is now growing evidence that these problems can also trigger sleep disturbance, high blood pressure, elevated heart rate, and increased psychological and physiologic stress.4,7 Elevated levels of the dangerous stress hormone cortisol are found in people with hearing loss and tinnitus — and cortisol elevations lead to cardiovascular disease, diabetes, bone loss, and early death.4
Scientists once thought that hearing loss and tinnitus were inevitable and irreversible consequences of aging itself. Not so, according to recent studies.8 The majority of hearing abnormalities in adults are now understood to be the result of two major kinds of noise: chronically elevated noise of the kind found in many industrial settings, nightclubs, and rock concerts along with “impulse noise,” or the sudden, sharp onslaught of a loud noise.
Ironically, it has been soldiers returning from recent wars who have advanced our scientific understanding of noise injury, especially those caused by impulse noise.9,10 Their exposure to gunshots, blasts, and other explosions has triggered an outpouring of research on how sound energy damages hearing.
How Noise Harms Hearing
Your ear is a complex organ with a deceptively simple task: turning the energy from sound waves into nerve impulses that your brain can interpret. Here’s what happens, in a nutshell: Sound waves, which transmit energy through the air, strike your eardrum, which vibrates very slightly as a result. Tiny bones in your middle ear, called ossicles, then amplify that slight movement by acting as little levers. The last part of that system of levers then pushes fairly strongly on a thin membrane, transmitting the vibrations to your spiral-shaped cochlea, or inner ear.
Your cochlea is filled with fluid and lined with specialized nerve cells called hair cells, which are sensitive to movement. When the fluid moves in response to pressure from the ossicles, hair cells generate minute electrical impulses. Those impulses then travel up your auditory nerve to the brain’s sound-processing areas. From there, higher-functioning parts of your brain interpret the sounds and respond to them appropriately.
Most of the time, this system works flawlessly, but like any system with moving parts, there is gradual deterioration. The bulk of the damage caused by loud noises is done at the level of the hair cells.15 To transmit a loud sound accurately, those cells must generate a burst of metabolic activity, consuming energy and generating reactive oxygen and nitrogen species.8,9 They also release copious amounts of the excitatory neurotransmitter glutamate, which is intrinsically damaging over the long haul.16,17
With each exposure to loud noise—whether continuous or sudden—your hair cells are literally working themselves to death. Free radicals and glutamate toxicity conspire to reduce blood flow to the cochlea, which produces additional oxidative stress, in the now-familiar cycle of tissue destruction.16,18-23
Ultimately, hair cells die, and when you lose hair cells, you lose hearing.9,20 Scientists now understand that the typical “age-related” hearing loss is nothing more than a drawn-out version of the destruction wrought by sound energy, spread out over a lifetime.8,23
Sudden loud noise also known as impulse noise seems to produce greater risk of hearing loss than continuous noise.9 If you encounter a very loud sound, especially on a background of already loud noise, you may suffer from acoustic shock injury (ASI). Symptoms of this sudden loud noise can produce ear pain, tinnitus, hyper-acute hearing or phonophobia (apprehension of loud noises), vertigo, and numbness or burning sensations around the ear.24 Psychological reactions to acoustic shock injury can include emotional trauma, anxiety, and even depression.24
Tinnitus is far and away the most common and irritating symptom that follows sudden noise exposure; 94% of soldiers studied on a firing range reported experiencing tinnitus.10
Tinnitus has many causes, not all of which are well understood, and no definitive cure.3,25,26 Tinnitus results at least in part from the excitatory stimulus of glutamate, which leaves hair cells producing electrical signals long after the original stimulus has gone.27,28 It may also result from impaired inhibitory signals from deep brain areas that normally “tune out” abnormal impulses arising from damaged hair cells.3,26
Finally, many people who suffer exposure to impulse noise are left with a condition called tonic tensor tympani syndrome, or TTTS.24 This disconcerting syndrome is caused by excessive sensitivity to loud noises, leaving the eardrum in a constant state of alertness, ready to tense up in response to the next burst of sound. The result is ear pain, often with a fluttering sensation or sense of fullness in the ear.
With all of the threats to your hearing from our noisy world, what can you do to protect yourself? More than you might think. Good physical protection is important and readily attainable through the use of low-cost earplugs, and boosting your intake of certain antioxidants and minerals can markedly reduce both short and long-term damage to your hearing, as we are about to see.
Defend Your Ears Physically: The Role of Hearing Protectors
Physical ear protection has long been considered the “last line of defense” after noise reduction and regulations.29,30 But until recently, most studies focused on noise in the workplace, where the threats are predictable and the solutions largely controllable. Recent evidence suggests that noise in everyday environments, like busy streets or entertainment venues poses equally great hazards. Nightclubs, for example, often produce peak sound levels as high as 107 decibels (dBA), while the maximum safe industrial sound level is considered to be 85 dBA, and for regular environmental exposure is 70 dBA.6,31-34 Urban dwellers may be exposed to chronic sound levels above 74 dBA simply during their daily activities, and above 79 dBA on public transit.6,31
Even if you stay out of noisy clubs, your leisure activities may put you at risk for unacceptable sound levels. Using power tools, driving loud vehicles, and hunting or target shooting are all examples of common activities that generate continuous or impulse sound that can hurt your hearing.36
Industrial workers often use “earmuff” type hearing protection, and some fields now even use advanced technologies like active noise reduction or noise cancellation, in which electronic circuits blunt the impact of noise. Such solutions are impractical for the average citizen, however.
The best hearing protection available to most of us is the simple earplug, which produces passive noise reduction just by blocking or dampening excessive sound energy before it lands on the eardrum. Experts believe that comfort should be the number one consideration, even above technical reduction of noise level. The argument, essentially, is that the “perfect” earplug that doesn’t get worn is of little use compared to a comfortable one that will be worn regularly.32
Another important feature of your hearing protection should be that it allows normal, natural communication. Too much sound reduction can reduce your ability to perceive speech naturally, or to hear and respond to sounds that warn of hazards.37 Excellent hearing protection is now available in the form of “social ear plugs” that allow you to reduce ambient noise levels while remaining attentive to the speech of those nearby.
When it comes to how much sound will be blocked, not all earplugs are the same. Like sun tan lotion with different SPFs, there are different protection factors for earplugs. This is known as the Noise Reduction Rating (NRR). The NRR is a rating system that has been set up by the Environmental Protection Agency (EPA) to represent how much noise the earplugs will block when worn properly. An important factor in determining a product’s NRR is its attenuation. The opposite of amplification, attenuation is any reduction in signal strength. Attenuation for hearing protection devices is determined by a panel of human subjects over a range of frequencies. The average attenuation is then used in calculating the NRR. The higher the NRR the more noise the earplug will block out.
Rock musicians are constantly exposed to high decibel sound and now an entire generation is experiencing tinnitus or noise induced hearing loss. The most famous example is Pete Townsend of The Who. Because musicians have to hear what they are singing and what their band mates are playing they need a well designed ear plug that allows them to hear the high notes and low notes of the music yet protect them from destructive sound. Musician earplugs should have an NRR of at least 12.
Choose your hearing protection, then, based on its comfort, its “social graces,” and of course its cost. Comfortable, effective, musician-grade earplugs can be found for less than $20 per pair from reputable manufacturers.
Defend Your Hearing With Supplements
Given the major role of oxidant stress in triggering noise-induced hearing loss, it’s natural to ask if antioxidant supplements might alleviate the risk. Once again, we can thank our soldiers for a large part of the answer; studies show that antioxidants administered before sound exposure can mitigate hearing loss in combat situations.9 What follows is a summary of readily-available supplements that you should use on a daily basis to optimize your body’s defenses against oxidant-mediated, noise-induced hearing loss.