Lend Me Your Ears
By Ann Constantino,
Published in the Humboldt Independent on June 1, 2021
Whether it’s Mozart or Led Zeppelin, birdsong or an elephant’s trumpet, your ears process sound the same way. Then your brain makes up your mind about what that sound means. Through a sophisticated and complex system, human hearing transforms sound waves into nerve impulses, which allow the brain to interpret the sounds as information about our environment.
Sound waves are produced when an object vibrates, creating a pressure wave of distinct frequency, pitch, and volume. This wave causes particles to vibrate in the surrounding medium, whether gas, solid, or liquid, and a sound wave is born.
The sound wave is then gathered by the outer ear and what follows is some pretty complicated physics to get that wave transformed into something the brain understands as sound.
Anatomy of the ear
Like the doorman at an exclusive club, the eardrum rejects some sound waves and accepts others.
The visible part of the human ear is called the auricle, or pinna. Smaller, and less efficient than many other mammalian auricles, ours is assisted by the long, narrow ear canal which focuses the sound waves onto the tympanic membrane, also known as the eardrum.
Like the doorman at an exclusive club, the eardrum rejects some sound waves and accepts others. The accepted sounds set off another series of vibration refinements in the “ossicles”, or three tiny bones in the middle ear.
The function of this miniscule bony chain (you may remember the hammer, the anvil, and the stirrup from your school days) is to convert sound waves into a form that can be absorbed by the watery fluid in the inner ear, or cochlea.
The cochlea is a roughly snail-shaped organ inside which the converted sound waves vibrate. This vibration stimulates the cochlea’s lining of thousands of tiny hair cells, which turn the sound waves into electrical impulses that are then transmitted to the brain for interpretation via the auditory nerve.
The human auditory system
The human auditory complex, while not possessing the greatest range of sound frequencies available for interpretation, does have special properties for hearing and interpreting language and music, two things considered to be uniquely human. Small children who hear more words early on tend to be more efficient learners. The melodies, harmonies, and rhythms of music are engaged by a wide spectrum of brain structures governing movement, emotion, and memory, as well as language.
The brain also has the capacity to zero in on certain sounds such as one instrument in a band or one voice at a crowded party. This selective hearing is not well understood but seems to diminish with age.
Even while sleeping, this selective hearing continues, enabling you to sleep through some inconsequential noises, but waking you to the ring of an alarm clock or a crying baby.
The brain also coordinates the signals from the two ears, giving us directional interpretation. Different positioning of the ears in some non-human creatures allows for even more refined directional perception, such as for various species of owls who hunt in the dark.
Like many things, hearing does not come with a lifetime guarantee. Gradual hearing loss is a normal part of aging for many. The progressive loss of hair cells reduces the kind and range of sounds that can be heard. Damage is exacerbated by frequent exposure to loud noise as well. Even young people are suffering this type of hearing loss from the volume being too high on their personal listening devices.
The eardrum can be damaged by an extreme sound that causes a rupture, lessening the ability to hear.
More specifically, an overload of high-pitched sound can damage the hair cells in the cochlea, making it difficult or impossible to hear sounds of higher frequencies. Interestingly, this can make the sentence “what time is it” sound exactly like “what kind is it” because consonants are more high-pitched than vowels.
Excessive buildup of earwax can cause hearing loss as the substance literally blocks the passage of soundwaves onto the sensitive structures.
The eardrum can be damaged by an extreme sound that causes a rupture, lessening the ability to hear. The eardrum can also be damaged when a build-up of pressure occurs. Inner and middle ear pressure is normally the same as on the outside of the body, and is regulated by the two eustachian tubes that connect the middle ear with the back of the throat. When the tubes are blocked through congestion of various causes, the pressure cannot be equalized. In extreme cases, the eardrum will become damaged.
Changes in altitude, scuba diving, or driving mountain roads can also contribute to pressure build-up in the ear and can be alleviated by swallowing, which opens the eustachian tubes.
Tinnitus is a persistent ringing or buzz (or sometimes other sounds) that only the sufferer can hear. It happens when damage to the hair cells, from aging or over-exposure to loud noise, causes them to send random electrical impulses that the brain interprets as sound. Treatment of tinnitus depends on its cause, but often a hearing aid will help.
Taking care of your ears is simple enough
Ditch the q-tips and use nothing smaller than a washcloth over your finger to clean them.
Let a healthcare provider take care of wax build-up, don’t do it on your own.
Turn down the volume. Earbuds or earphones are too loud if someone else can hear them. Wear earplugs if you are around unavoidable loud noise or operating loud machinery. If you have to ask someone to speak up because of ambient noise, it’s too loud.
Find out if any medications you are taking can cause hearing impairment.
Let your ears rest. Silence is golden in more ways than one.
See your provider if you have a sudden change in hearing ability, or if you have pain or itching inside the ear.
Helen Keller said, “Blindness separates people from things, deafness separates people from people.” In this time during which we have learned well how precious our connections to people are, be good to your ears. Turn that Mozart down.
Ann Constantino, submitted on behalf of the SoHum Health’s Outreach department.