Earbuds and earplugs -- A heads-up on hearing health - Part One


NOTE: This is the first post in a two-part article. Click here to read part two!

As a voice actor, you figuratively need “ears” for judging your performance. But these days you’re probably also your own audio engineer, so you also really need ears for judging the quality of your audio.

How’s your hearing? Probably significantly worse than your counterpart a generation or two ago. Our ears evolved in a world where the loudest sounds were the roar of a waterfall, a clunk of two rocks, and the occasional bolt of lightning. Today’s world and your own listening habits can be murder on your auditory system. How can you protect your hearing?

The purpose of this article is to bring these issues to your awareness. It is necessarily only a summary and details are generalized. To fully appreciate what hearing dangers exist in your environment, and to determine the extent to which you should be concerned and/or take precautions, and what precautions are best for you, please look further into the issue or consult a hearing health professional. If you have any hearing difficulty, noticeable hearing loss, ear ailment (including but not limited to pain, discharge or pus), or want expert advice, please consult your physician or a hearing specialist promptly.
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Whatever your age, your hearing won’t be any better than it is right now. And odds are, your hearing right now isn’t the equal of your professional counterpart a generation ago.

In the U.S. alone, 10-million people have Noise Induced Hearing loss (NIHL). It’s small wonder, what with decades of having used earbuds, headphones (and before that, boom boxes), humongous car stereos, constant music, home theater systems and other sound blasters. In addition, there’s the effect of rock concerts and today’s environmental din, including traffic, trains, subways, leaf blowers, jackhammers, jets and everything else. Not to mention that in your home studio you might wear headphones for several hours a day.

What you once could hear, and why now you don’t.

Ideally, a young person can hear as high as 20,000 cycles per second (20 kHz), even a little higher, which might be subjectively noticed in a live flute, cymbal or violin performance, or on excellent vinyl played though a high-fidelity system. But that upper limit is largely theoretical. Most people do not hear above 10 kHz anywhere near as easily as they hear below 8 or 10 kHz, and by middle age, most people don’t hear above 16 kHz no matter how carefully they listen.

If you’re in your fifties, don’t be surprised if you can’t hear a pure 11,000 Hz tone. (It is, indeed, spooky to play a 15,000 Hz tone and see it register clearly in your software’s volume meter, while you hear nothing!)

Since the human voice and ear are both focused on frequencies well below that (the voice consists mainly of tones from 1,000 to 5,000 Hz), most people don’t notice the presence or absence of sounds at the extremes. These outer ranges (above 10 kHz and below 60 Hz) are not necessary for “broadcast quality” and are not a significant part of the human voice. In fact, including frequencies that are beyond the vocal extremes can be detrimental to the sound of your voice recording, in the form of boominess, stray rumble or excessive sibilance.

But if you play with your equalizer settings, you’ll notice that tones outside the 1,000-5,000 cycle range do have very significant effect on your recording. Sibilance, for better or worse, ranges mainly from 7,000-10,000 Hz. Although some sibilance is necessary for S sounds to be intelligible, you may want to reduce excess sibilance by somewhat lowering frequencies in that range.

But to know if sibilance is excessive, first you have to hear it, right?

So if you’re doing the EQ and mixing on a job, it pays to have preserved all the hearing sensitivity you can. Sure, a graphic equalizer or display will help you see what your software is doing, but, just as the human hand is a carpenter’s most sensitive smoothness gauge, your ear is the best gauge for fine-tuning audio.

As Edge Studio’s Director of Technology George Whittam says, “Use your ears. If it sounds good, it is good.”

How vulnerable is your hearing?

But in this context, George adds, "But that's only if you've had your hearing tested first!"

In today’s world, your hearing is very much at risk, even if you live on a farm. Exposure to sound levels over 85 dB is hazardous over time.

A typical rock concert (or an MP3 player at full volume) easily sustains at least 110 decibels, which can cause permanent hearing loss in just 15 minutes or less. According to the National Institutes of Health, exposure to even louder sounds can cause permanent hearing loss in as little as one minute.

Here are typical sound levels for various corners of our daily lives. Anything above 85 dBa is cause for concern, and as sound get louder, the length of time you can endure it without damage becomes shorter. In other words, hearing damage is a function of both the sound level and time. But at some point, damage can be immediate, and remember that all these numbers are just a generalization.

Air conditioner or dishwasher 50-75 dBa
Hair dryer 60-95
Power lawn mower 65-95
Food blender 80-90
Heavy traffic 85
Noisy restaurant 85
Truck or tractor 90
Shouted conversation 90
Subway 90-115
Typical nightclub 97 dB
Leaf blower 110
Symphony concert 110
Rock concert 110-120
Squeaky toy (near ear) 110-135
Football stadium crowd 117
Ambulance siren 120
Common MRI 85-125
Automobile stereo (factory installed) 125
Airplane taking off 140-150
Shotgun 170
Rocket launch 180

Respect your ears as you would any sensitive instrument.

It’s ironic that people take great care not to damage a highly sensitive professional microphone, yet take their ears for granted. The ear’s intricate design puts mics to shame. Our biological hearing device is an amazing chain of tiny, super-sensitive components -- all the more amazing when you consider that they evolved from gill parts and reptilian jawbones and handle virtually every physical and biological contingency except unnaturally loud noise.

Theoretically, a human can hear as high as 25,000 Hz (a wave of about half an inch) and as low as 16 Hz (70 feet). The loudest audible “safe” sound has 100 trillion times more energy than the quietest we can hear.

You probably learned in high school that the ear consists of an eardrum (tympanic membrane) and three little bones (ossicles) shaped like a hammer, anvil and stirrup in the middle ear, and they somehow tickle hairs in the inner ear that send nerve signals to the brain. Well, it’s a good deal more complicated than that. We’ll refer you to Wikipedia or someplace for all the details.

Suffice it to summarize some of the highlights:

  • The “hairs” are actually hairlike projections (stereocilia) that sit on special sensory cells. (They’re not hairs, and they don’t grow back, but from here on, we’ll just call them hairs.)
  • The ossicles’ motion amplifies gentle sounds as much as 50 times. Loud sounds are dampened by special muscles. Weakness or irregularities in these muscles contributes to tinnitus. (More on tinnitus below.)
  • The Eustachian tube equalizes inner and outer air pressure. Otherwise the eardrum could not vibrate.
  • The eardrum isn’t the only membrane in there.
  • The ear is designed to largely reject sounds transmitted by bone.
  • A trio of coiled tubes (cochlea), containing those hairlike sensory cells, is connected to the acoustic nerve.
  • In the cochlea, air vibrations are converted to fluid vibrations.
  • As a wave, caused by sound, moves through the fluid-filled cochlea, it stimulates a membrane running the length of the cochlea. This membrane, being of increasing thickness, vibrates at a certain point along its length according to the frequency. The result represents not a single pitch, but is more like a graphical waveform. The membrane bumps some of the hairs, causing them to bend and allow chemicals to enter, which interact and create an electrical current that is sent to the brain. The brain sorts it out -- dominant pitches, overtones, amplitude and all. (We apologize to every anatomist who finds this explanation either faulty or oversimplified, but please take its point – the ear is not just three little bones, 20,000 hairs and a tom-tom. Hearing anatomy)
  • The ear’s apparatus also includes mechanisms, not hearing-related, for knowing which way is up (using particles of calcium carbonate), and for sensing inertial changes in three planes.
  • The ears work together with the brain to serve also as echolocators, determining which direction a sound is from.

    In other words, it’s almost a wonder that it all works in the first place!

    How do we lose hearing due to extremely loud or sustained loud sound?

    Obvious answers include damage to the ear drum, or to the fine bones of the middle ear, from extremely loud sound that causes sudden damage. But the nefarious culprit of gradual hearing loss is the loss of those hairs’ functionality, possibly simply due to additional wear and tear. Louder sounds make them more quickly worn and torn.

    How so we lose sensitivity to pitch as we age?

    No one has a certain answer. One theory is that, since sound waves travel down the cochlea and the highest frequencies are sensed at the cochlea’s entrance, the sensors at the entrance are exposed to every sound encountered, thus wearing out sooner over time. Or it might be that the entrance is more exposed to food-based and environmental chemicals and medicines that can do it harm. Or it might be due to an accumulation of lipofuscin granules, a product of cellular wear and tear throughout the body. Or it might be all of these and/or other factors.

    Whatever the causes of age-related hearing loss, it happens. You can’t stop getting older.

    Other factors in hearing loss

    Ear wax (cerumen). The presence of a certain amount of “wax” in the ear is normal. It keeps the ear canal skin healthy and even repels insects (eeuwww!). Ordinarily, the ear is self-cleaning – wax migrates to the exterior, dries and falls out or is washed away. But sometimes if you regularly use earplugs or earbuds (see below), it can build up. If you haven’t also been swimming for a long time, and don’t rinse your ears while showering (gentle spray, at moderate temperature, please!) or use an ear wax removal kit, it could accumulate. But note that purposely exposing your ear canals to a shower stream might not be advisable for everyone; some people have narrow ear canals, and water could get trapped, promoting infection or other complications if the water is cold. Three are over-the-counter wax removal kits, but don’t use one habitually unless advised by your doctor. It can irritate the canal and delicate eardrum over time.

    Do NOT clean your ear canal by inserting a cotton swab or other object -- there’s potential for irreparable damage. And if you suspect a wax plug has developed, don’t simply spritz it with a rinsing bulb; once a plug has formed, that could just push it in farther. If you suspect a build-up, use a wax softening kit or get checked by a healthcare professional.

    And if you experience any sudden hearing impairment (or suddenly notice impairment), consult your doctor without delay.

    Earbuds. These seemingly innocuous little critters embody a variety of sins, so we’re giving them special mention here. They are not functionally the same as headphones, let alone far-away speakers.

    Children and adolescents have been found to have a greater rate of hearing impairment in recent decades. The rate of hearing loss among teens is 30% higher than a generation ago, and (screening programs being neither sophisticated nor universal) many cases are probably undetected. Tinnitus (again, more below) among young people has also increased.

    For the first time in history, millions of kids’ hearing may be worse than that of their parents or even grandparents. Earbuds surely contribute hugely to this trend.

    To reach harmful sound levels with earbuds on your smartphone, you need only crank the volume above 50%. Buds are so much closer to the eardrum than headphone diaphragms that they can sound about 9 dB louder. We hear someone saying, “Ah, but therefore I can turn down the volume control.” The problem with that is, people don’t. In fact, to block out noise from their surroundings, they turn the volume up!

    Irritation from the insertion of earbuds can increase wax production. Over time, it can build up, and the buds can even compact it, creating a dam. On the Internet there are a lot of questions about the advisability of actually using earbuds to clear out ear wax. We’re not sure how this would be done, but in any case, no ... there are more effective ways to clean your ears, and as we said, ordinarily it should not even be necessary.

    Tinnitus. A variation on the inability to hear certain frequencies is tinnitus (pronounced TIN-ih-tus), commonly referred to as “ringing” in the ears, but it might manifest itself as an omnipresent tone, or roaring, clicks or buzzing. Tinnitus can occur in young adults (possibly resulting from exposure to loud sound levels), but it becomes more apparent as you get older.

    It, too, is caused by damage to the “hairs” as they send random signals to the brain. Damage to previously mentioned muscles can also be a cause. It can also be caused (temporarily) by ear wax, or the cause might be genetic. There are also less common causes, such as injuries, Meniere’s disease, medications, tumors or abnormal blood circulation and other possibilities. Smokers have higher tinnitus risk. (Since your living depends keeping your vocal equipment intact for a good long time, we hope you’re already not smoking!)

    We’re not experts in this subject, but have heard that some tinnitus might not be a “sound” at all, but rather an attempt by the brain to create an expected sound when it is not present. Whether that’s the case or not, a member of our staff (who has a mild case, just enough to be noticeable at times in a quiet environment) has noticed this: His tinnitus manifests itself as a high-pitched tone, and if he whistles loudly for several seconds, then stops, the tone will have temporarily diminished or even gone away. Whatever the reason, he says it removes the distraction enough that he can focus on what he’s reading in bed. As for his work in the booth, he says his case is relatively minor, and during most of the day either it is unnoticeable or his mind is too much involved in work that he doesn’t even know if the tone is there.

    Air pressure.Sound itself is a series of rapid changes in air pressure, but here we’re talking about general air pressure. As we’ve noted the ear has a mechanism for equalizing pressure inside the ear, but it can be temporarily blocked or even permanently damaged. Sudden changes in air pressure can cause damage to parts of the ear, or cause temporary hearing impairment, such as when flying or scuba diving.

    Medicines and diseases. Medications, such as some antibiotics and chemotherapies, can affect hearing, sometimes temporarily, but possibly permanently. If you regularly use aspirin, NSAIDs or acetaminophen, check with your doctor or pharmacist. Chronic diseases can also cause hearing loss by interrupting blood flow to the ear or brain. Suspects include heart disease, stroke, diabetes, high blood pressure, autoimmune diseases such as rheumatoid arthritis, and growths.

    Next week:

    Various ways you can help protect your hearing.

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    Technical notes if you play test tones:

    • To avoid possible damage to your speakers, don’t play a pure tone for long, and especially avoid higher than normal volume even for a short time – even if you can’t hear the tone, your speakers could be overworking themselves to the point of displacement or meltdown.
    • Without an excellent sound system or a true hearing test, you might not be hearing as well as you think. For example, you might think you’re hearing 20,000 in a recording but actually are hearing lower-frequency harmonics or overtones created by the speakers or headphones. Similarly for very low tones (e.g., 30 Hz).
    • For an accurate hearing test, see a healthcare provider or other hearing professional.

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    ADDITIONAL READING:

    Generation deaf: Doctors warn of dangers of ear buds

    Nat Lauzon on Hearing Loss and Hearing the Details. Nat Lauzon, voice artist and DJ.

    How we hear different pitches. Interactive Biology

    Eminent Technology's Multimedia Speaker Test. Test tone files at various frequencies. IMPORTANT: Please read the page’s warning, do not exceed normal listening levels, and do not play tones for longer than recommended.

    Pilot Survey of Subway and Bus Stop Noise Levels. Journal of Urban Health

    Noise-Induced Hearing Loss. National Institute on Deafness and Other Communication Disorders

    Scientists Solve Mystery Of Ear-Splitting Sounds. NPR.

    Artists and celebrities who have had hearing loss: (This list dates from at least 10 years ago, and is probably older)

    Mayo Clinic: Earwax blockage.

    10 Common Noises That Can Cause Permanent Hearing Loss. Huffington Post

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