Not all hearing loss is the same. In fact, there are two main categories of hearing loss, and while they are both characterized by difficulty hearing, there are some key differences that can affect the severity of hearing loss and how it’s treated.
1: Sensorineural Hearing Loss
Sensorineural hearing loss occurs when there’s dysfunction or damage to the inner ear, which is home to an organ called the cochlea. The cochlea is critical to our ability to hear; it encodes sound information into electrical signals and sends them to the brain to be perceived as sound. The way it accomplishes this is via thousands of hair-like sensory cells.
Causes of Sensorineural Hearing Loss
When those sensory cells in the cochlea sustain damage, they can no longer transmit electrical signals to the brain, which results in sensorineural hearing loss. Many things can damage these cells, including:
- The natural process of aging. As we grow older, our bodies decay. This is completely normal, and it happens to cochlear sensory cells just like it does to any other cells in our body.
- Exposure to loud noise. Loud noises have large, powerful sound waves that enter the cochlea like a hurricane. These can flatten or break the cochlear sensory cells.
- Cardiovascular conditions. Like most cells in our body, the cochlear sensory cells are hooked up to our blood flow, and they need the nutrients and oxygen that blood supplies in order to function. Conditions such as hypertension and heart disease, which affect how and how much blood moves around the body, can cause the cochlea to receive less blood than is necessary to function properly.
- Ototoxic medications. These are medications known to damage the inner ear’s cells as a side effect. These drugs are often critical in treating other health conditions, such as serious infections, cancer and heart disease.
As you can see, both age-related hearing loss (presbycusis) and noise-induced hearing loss fall under the umbrella of sensorineural hearing loss, making it by far the most common of the two types of hearing loss.
What Sensorineural Hearing Loss Sounds Like
The cochlear cells are specialists, not generalists. Each cell collects and transmits its own specific pitch from the spectrum of audible (to humans) sounds. When a sensory cell is destroyed, you will no longer be able to hear the pitch that cell “specialized” in.
The first sensory cells to die off are typically those that detect high-pitched sounds. This is because they are the smallest and, therefore, the most delicate, and they are the closest to the mouth of the cochlea, meaning they get hit by incoming sound waves first. In practice, that means that in the case of presbycusis, they’re the first to wither away, and in the case of noise-induced hearing loss, they bear the brunt of the force of loud noises.
All that to say, sensorineural hearing loss is often characterized by difficulty hearing high-pitched sounds, such as birdsong or the phone ringing. It is also more difficult to hear human speech, as much of human speech takes place in the higher pitches. You may especially struggle to hear the voices of children, women and other people with high-pitched voices.
2: Conductive Hearing Loss
In order for the cochlea to receive sound information, sound waves must first travel down the ear canal, past the eardrum and through the middle ear. Conductive hearing loss occurs when this sound highway is obstructed in some capacity.
Causes of Conductive Hearing Loss
Anything that blocks or damages the outer or middle ear leads to conductive hearing loss. This includes:
- Foreign objects stuck in your ear. This is especially common in children.
- Earwax blockage. Earwax is a naturally occurring substance in the ear and usually sheds naturally, but it can build up in the ear canal and compress into a tight blockage.
- Ruptured eardrum. The eardrum is a taut membrane that vibrates when struck by incoming sound waves (much like its namesake, a drum). A tear in this membrane prevents it from vibrating.
- Ear infections. When the middle ear fills up with fluid, it can become infected, which affects the way sound waves travel through the middle ear.
- Structural abnormalities or tumors. Conditions like otosclerosis, cysts and ear tumors may all grow in such a way that they block the ear canal.
What Conductive Hearing Loss Sounds Like
Since conductive hearing loss is often caused when sound is completely prevented from reaching the inner ear, it affects all pitches somewhat equally. Typically, conductive hearing loss will cause all sounds to seem muffled or quieted, like you’re wearing earplugs you can’t take out.
Hearing Loss Treatment
How hearing loss is treated will depend on the type of hearing loss. Conductive hearing loss can be reversible and can often be treated quite successfully by removing the impediment from the ear, such as getting your ears professionally cleaned or a tumor surgically removed. For cases where conductive hearing loss cannot be treated by removing the blockage, cochlear implants bypass the ear canal and the ear organs to directly stimulate the auditory nerve, sending sound straight to the brain.
Sensorineural hearing loss is rarely reversible. For this type of hearing loss, hearing aids are the most common treatment option. With sophisticated sound processing, they can collect the sound waves that enter your ear, isolate the pitches that you struggle to hear due to cochlear cell decay and amplify those pitches directly, effectively filling in the gaps in your hearing.
If you’re ready to start your hearing loss journey, schedule a hearing test at Gulf Coast Audiology. Through diagnostic testing with our expert team, we can determine what type of hearing loss you have and recommend the best treatment option for you.