Your ability to hear is one of five precious senses that you use daily to communicate, navigate and enjoy the world. Think of all of the sounds we hear each day: a loved one’s voice, a child’s laughter, a pet purring or barking, music on the radio, news reports, and the voice on the other end of the phone. Some sounds contribute to our enjoyment of life, while others contribute to our safety: car horns, sirens, smoke alarms. Hearing matters!
Our sense of hearing enables us to work, socialize and communicate important information. But how much do you really know about your ears and the job they do?
How we hear
When sound waves reach our ears, the outer ear funnels them into the ear canal, which they travel through toward the eardrum. This causes the eardrum to vibrate, which in turn vibrates three tiny bones located in the middle ear, which amplify the sound vibrations so they can reach the inner ear. In the cochlea, a snail-shaped structure filled with fluids in the inner ear, the vibrations stimulate tiny hair cells to bend and convert vibrations into the electrical signals that the auditory nerve carries to the brain. Our brain interprets these signals into what we perceive as sound. It’s quite a journey, but it happens in milliseconds, and thus we can hear.
What we hear
Sound is measured in decibels. People with good hearing can perceive a range from 1 to about 130 decibels:
- Your own breathing: 10 decibels
- A soft whisper: 30 decibels
- Normal voice in conversation: 50-60 decibels
- A plane taking off: 130 decibels (standing outside, close by)
- A firecracker: 140-150 decibels
Loud sounds may cause hearing damage both instantaneously and cumulatively over time. Very loud sounds (about 120 decibels and up) take a shorter period of time to cause hearing loss, but long exposure of moderately loud noises (around 70 decibels and up) can also cause hearing loss over prolonged periods. In general, the longer the exposure to any noise, the more significant the risk you’ll suffer hearing loss from it.
Noise over 70 decibels—about the sound of a washing machine or dishwasher—experienced over several hours may start to damage your ability to hear. Very loud noises over 120 decibels—like a firecracker going off close by–can cause immediate harm to your hearing.
Types of hearing loss
The two main types of hearing loss are sensorineural and conductive.
Hearing loss resulting from inner ear damage is called sensorineural hearing loss. It results from damage to or dysfunction of the inner ear’s cochlea or the auditory and neural pathways to the brain. Sometimes it’s present at birth, but it can also be caused by ongoing exposure to loud noises, music, or even medications. Sensorineural hearing loss is untreatable by either medicine or surgery and is permanent.
Noise-induced hearing loss– a form of sensorineural hearing loss–is the only hearing loss that is completely preventable.
Have you ever left a loud sporting event or rock concert and couldn’t hear as well as when you got there? That’s likely a temporary hearing loss which could return in a few hours or a couple of days. Hearing loss can be temporary, as long as critical parts of our delicate hearing system have not been damaged beyond recovery.
Here’s why: Those little hair cells in your ears’ cochlea—think of them as similar to blades of grass—bend more and more as sound grows louder and louder. But if no permanent damage is done, they will straighten out again after a period of time and recover.
Humans are born with about 16,000 tiny hair cells in the cochlea, which enable the brain to hear. We can damage or destroy 30 to 50 percent of these cells before hearing loss will register on a hearing test. Unfortunately, by the time you’re experiencing hearing loss, the majority of those damaged hair cells won’t recover and hearing loss will be permanent. Once these tiny hairs are destroyed, they can’t regenerate.
People often first notice hearing loss when conversing in noisy places, asking conversation partners to repeat what they said. Eventually, as hearing loss progresses, it becomes hard to understand conversations even in quiet settings.
To prevent noise-induced hearing loss, pay attention to the sounds in your environment and that of your children. If a sound is too loud, causes discomfort or annoys you, seek a quieter environment or use protective hearing devices such as protective earmuffs, noise-cancelling headphones or foam earplugs to protect yourself.
Conductive hearing loss
Problems with the middle or outer ear can cause conductive hearing loss. In this condition, the inner ear functions normally, but an obstruction or damage to the middle or outer ear causes the loss. Fortunately, this type of hearing loss is often treatable and typically temporary in nature. Causes include ear wax buildup, and ear infections such as swimmer’s ear, a painful bacterial infection that can cause the ear canal to swell shut.
Do you have hearing loss?
If you suspect you are suffering from hearing loss, consult your family doctor or an audiologist. You can take steps to slow your hearing loss progression. The average person with hearing loss waits 7 years to do something about it—time in which they could have been protecting the hearing ability they have left.
In our next blog, we’ll discuss ways to protect your hearing.