Hear Today, Gone Tomorrow
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Boom, Bang Ka-Pow. Reading these words will never have the same impact as hearing the real sounds in action. Written words (and hand gestures) are the way an ever-growing part of our population communicates, due to the worldwide increase in hearing loss.
Combine modern music players, cellphones, cars, trains, planes, lawnmowers and construction tools, with our need for dangerous decibels at concerts and on TV. For even more of an earful, there has been an increase in heavy machinery and loud factories thanks to mass industrialization.
Now a music player or cellphone can deliver a death metal concert straight into your ear canal which, unless you want a permanent ringing soundtrack, is not a good thing. Worst of all, hearing damage is permanent and irreversible. If you need more motivation to dial down the volume, know that chronic noise affects your health. It increases anxiety levels, elevates blood pressure, disturbs sleep and even causes you to eat more in restaurants. To prevent these health dangers and permanent loss of hearing, use this guide to ensure you're always equipped with surround sound.
Sound Travels
To understand how hearing happens, imagine a fluid-filled, snail-shaped corridor (cochlea) .1 which contains a structure called the Organ of Corti, which consists of inner hair cells and outer hair cells that are topped by a large number of stereocilia. When sound is relayed by the outer and middle ears into the cochlea, a wave goes through the fluid, strumming the hair cells that are strung across the interior. This movement is then transformed by the hair cells into electrical energy, which is sent to the auditory cortex in the side of the brain (in the temporal lobe) where it's understood as sound. Exposure to loud noises for extended periods causes those hairs to lose their ability to snap back into place and, in some cases, break off.
Noise-induced hearing loss (NIHL) is caused by two types of noise: sudden bursts (such as guns, car backfires or fireworks) or continuous exposure to loud noise (such as working on an airport runway or regularly listening to a dangerously loud MP3 player). At first the hairs sustain what is called a temporary threshold shift (TTS) - a brief shock to the system. If this type of noise exposure continues over a prolonged period of time, permanent changes may occur. This is called permanent threshold shift (PTS) and typically affects the higher speech frequencies around 4 000 to 6 000Hz. This is due to actual damage - or even death - of the cilia. Initially, the sufferer might not notice the hearing loss, but rather a difficulty understanding what people are saying, particularly when there's background sound. As the high-tone hearing loss worsens, an obvious hearing loss appears.
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The first warning sign of permanent hearing loss comes in the form of tinnitus, a constant noise defined as the perception of sound without an external stimulus. Non-pulsatile tinnitus is the high-pitched ringing sound one often hears, and research suggests that the tinnitus is generated in brainstem structures in response to damage to the cochlea. It can affect sleep, concentration and even mood. The cure in the Middle Ages was to pop the eardrum (tympanic membrane) [2]. Thankfully, we’ve moved on since then.
While there is no effective cure for tinnitus at this stage, one can recover with a period of ‘rest’ for the background noise levels to fall. If the threat of both these complications isn’t enough to make you drop the volume levels, consider that repeated exposure to excessive noise may increase your risk of developing an acoustic neuroma, a benign nerve tumor that grows inside the skull and increases hearing loss, according to a study in the American Journal of Epidemiology. Not ideal. See below for the culprits that cause tinnitus and hearing loss and the solutions to beat them.
Hear no Evil
Without question, noise exposure is the number one risk factor for acquired hearing loss these days. Other factors include genetics, disease, specific medication and a few others. But these all pale in comparison to the damage caused by noise. One common myth with hearing loss is that you lose it naturally as you grow older due solely to biological factors. Not true. Hearing loss associated with old age (known as presbycusis) is at least partly related to noise exposure. So loud noises are the enemy, no matter your age. Here’s a list of the most common noise offenders.
Portable Music Players
Current research shows that portable music players are public enemy number one when it comes to sabotaging your sense of sound. The damage caused by noise exposure of this type is a function of both the loudness as well as the duration of the sound. The tendency for young people to spend every spare moment listening to a MP3 player with earphones in is placing them at higher risk. And research provides proof. In a study of 238 students at West Virginia University, 50 percent of the students were exposing themselves to potentially harmful loud music.
Most of the students considered the hearing loss to be serious, but 76 percent of the students believed that they would not lose their hearing until a greater age. These and other studies highlighted how hearing loss is perceived to be age related. Unfortunately, being male doesn’t help things as we tend to think we’re invincible. In a study done by the University Medical Center in Rotterdam, they found that most adolescents – especially male students – indicated that they often played their MP3 players at maximum volume. Although they appeared to be generally aware of the risks of exposure to loud music, they felt little vulnerability. In the West Virginia study, 66 percent of the students had experienced tinnitus but 58 percent of those students reported not being concerned about it.
Sound Solutions
Typically, a person can tolerate about two hours of 91-decibel sound per day before risking hearing loss. The answer seems pretty simple – keep your volume below 75 decibels. To do that, see if your MP3 player has a volume-limit function. iPod users can download a volume limiter. A quick rule of thumb. You should be able to hear someone that’s an arm’s length away from you. However, it’s not that easy. When there’s background noise from the gym, car or construction site, we tend to pump the volume up. At full volume, music players can reach over 100 decibels, only slightly softer than a chainsaw and loud enough to damage your hearing in five minutes.
If you want some protection, choose your earphones carefully. Invest in a decent pair of noise-blocking headphones. When music has more low-frequency sound waves, you perceive it as louder even at a lower volume. Both those tricks will help you to keep the volume down. Lastly, if you ever experience any ringing in your ears, see an ENT specialist or audiologist.