Even though my youth was spent in several Latin American countries, we had our share of visits by rock and roll bands, and my friends and I didn’t miss the chance to go see them. In this way I got to see bands like The Hollies, Santa Esmeralda, Van Halen, and Queen, and solo performers such as Donna Summers, Joe Cocker, and Peter Frampton. Besides the big international bands and singers, we also had our fill of concerts by local bands. And because we were young, we also partied a lot and danced to the rhythms of the waves of rock and roll, disco, punk, and new wave genres that over the years washed over our musical landscapes. What all the foregoing had in common was the fact that we were exposed to very loud sounds, so much so, that we often woke up the next morning after a concert or a party with our ears ringing. And we considered this to be cool!
What can I say? We were ignorant, and no adult had the good sense to call us out on our folly. Now fast forwards 40 years, and what do we have? Tinnitus and hearing loss! How does this happen? Let’s look first at how hearing takes place.
Sound waves reach the ears and make the ear drum vibrate. On the inside surface, the ear drum is attached to a small bone called the malleus, which is attached to another bone called the incus, which is in turn attached to yet another bone called the stapes. The stapes is connected to a snail-shaped organ called the cochlea. These bones have the function of amplifying the sound waves. Vibrations of the ear drum transmit through these three bones to the cochlea, where they are detected. The way this happens is that the cochlea is filled with fluid, and when the stapes vibrates upon the cochlea, it creates waves in the fluid that travel the length of this organ. The cochlea has hair cells which are moved back and forth in response to the waves travelling through the liquid, and these cells have specialized projections called “stereocilia”. Some of the hair/stereocilia structures are sensitive to waves of longer wavelengths (low pitch) such as those produced by the sound of a drum, while others are sensitive to waves of shorter wavelengths (high pitch) such as those produced by the sound of a whistle. When stimulated by these sounds, the stereocilia create an electrical signal that travels to the base of the nerve cells where they are relayed to neurons, which transmit the signal to the brain. The brain integrates these signals from both ears and creates the sensation of sound.
Evolutionarily speaking, the human ear is not designed to deal with very loud sounds, just the opposite. The ears of our animal ancestors, as most other animals, had to detect the faint sounds of a stalking predator or of a prey slipping away. In nature, loud sounds are the exception rather than the rule. Prolonged exposure to very loud sounds has a destructive effect on the hair cells of the cochlea. There are about 16,000 of these hair cells in this organ, and when one of these cells dies, it cannot be replaced. In fact, by the time a hearing test detects a hearing loss, about 30-50% of the cells in the cochlea have been damaged or have died.
Loudness is measured in a unit called a decibel, but this unit is not linear. Regular human speech is 65 decibels, while busy urban traffic at 85 decibels is four times louder than human speech, and the common loudness of a rock concert at 115 decibels is ten times louder than human speech. Continuous exposure to 85 decibels for 8 hours can produce hearing loss, while at 115 decibels, this can happen in one minute. Consider then that the loudness of some rock concerts has been measured at more than 140 decibels! It has been estimated that by 2050 there will be 50 million people suffering hearing loss from exposure to very loud music. Additionally, in many people when the brain ceases to receive the inputs from dead cochlear hair cells it creates a buzzing sound called tinnitus, which can range from barely perceptible to a debilitating loud sound.
Hearing loss can create communication problems at work and with family, friends, and acquaintances leading to emotional problems and social withdrawal. As if that were not enough, hearing loss has another consequence: dementia! Epidemiological studies have found that individuals with hearing loss are at a greater risk of dementia. The good news is that wearing hearing aids does not only allow you to hear better, but it also reduces your risk of dementia by half. Unfortunately, only 14% of adults with hearing loss wear hearing aids.
So, to wrap this up, if you attend concerts and other events in an environment with loud sounds, please wear ear plugs. Losing your hearing is not cool (take it from me, I learned it the hard way). Also, if you experience difficulty hearing well, get yourself tested for hearing loss, and if you have it, please wear hearing aids. Not being able to communicate well with others and developing dementia is also not cool. Today’s hearing aids are barely detectable, so don’t fret about that. Science has provided us with the understanding and the technology to deal with hearing loss. Accept this gift of science, and wear the hearing aids!
The image by Cenveo is used here under a Creative Commons Attribution 3.0 license.