3 Types Of Hearing Loss - Conductive, Sensorineural, Mixed
Hearing is a complex sensory function that many people take for granted. It requires the precise coordination of physical structures in the ear to sense vibrations, or sounds, and the mental functioning in the brain to interpret those sounds.
A breakdown in functioning or deficiency at any point in this system can result in hearing loss.
How Is Hearing Loss Diagnosed?
Hearing loss can be a subtle change that you don’t really notice until it interferes with your daily life. Exposure to loud noises or other hazardous conditions may erode your ability to hear sounds of a certain frequency or distinguish between different tones. When you realize your television volume is on high or you constantly have to ask people to repeat themselves, it could be time to get your hearing checked.
There are several treatments for hearing loss, but your specific type of hearing loss must be identified. Diagnosis is based on testing. Common tests for hearing loss include:
Tuning Fork Tests — When you strike a tuning fork, a small, two-pronged metal instrument, it vibrates at a particular frequency. By holding the end of the tuning fork against a solid surface, you can hear the tone created by that vibration. A tuning fork is used to perform Rinne and Weber tests for hearing loss.
The Rinne test compares the amount of time that the tone of a tuning fork is conducted by the air, as compared to the tone conduction by your bone. The doctor strikes the tuning fork and places it on your mastoid bone, just behind your ear, and measures how long you continue to hear the sound of its vibration. When you stop hearing the tuning fork, the doctor holds it next to your ear without touching it to anything and measures the length of that sound.
By comparing the length of these two sounds, the doctor can locate your hearing loss. Someone with normal hearing will hear the sound of the tuning fork near his ear for twice as long as when it is touching the bone behind his ear. If one sound is longer, then conductive or sensorineural hearing loss can be diagnosed.
The Weber test also uses a tuning fork to assess hearing loss. The doctor will strike the tuning fork and touch it to the middle of your head. If you hear the sound equally in both ears, your hearing is normal. A stronger sound in one ear will indicate a hearing loss, though the deficiency may be in the stronger or the weaker ear.
General Screening — Your doctor may perform a general screening test to check for hearing loss. He might ask you to hold your hand over one ear and see how you respond to various questions. He will change the pitch of his voice to determine if there are any potential deficiencies in your hearing, and he’ll repeat the test on your other ear. If the general screening shows any potential hearing loss, it’s usually followed up with more specific tests.
Audiometer Testing — This test is administered with earphones. The doctor plays tones at different levels and frequencies in each of your ears and asks you to indicate the ear where you hear each sound. Based on the frequency of the tones he plays and your responses, he is able to chart how each ear performs and the range of your hearing abilities. These can be compared to standard ranges to determine if there is any hearing loss.
Audiometer testing quantifies the pure-tone average (PTA) in each ear. A PTA of 25 or less means the ability to hear normal speech. At 70 or above, a PTA would indicate a profound hearing loss. With functionally impaired hearing, you would score about a 40 on the PTA in both ears. People who are considered functionally impaired tend to benefit the most from some type of sound amplification device.
Physical Exam — By examining your ears, your doctor can determine if there is a physical cause for any hearing loss you might be experiencing. Inflammation due to infection can impair the delicate structures of your inner ear from working properly. A build-up of wax can also block your ability to hear properly. Your doctor can diagnose these problems very easily by simply looking in your ear with an auriscope, a hand-held instrument with a small cone on the end.
Most of these tests are minimally invasive, easy and not painful at all. During a physical exam, your doctor will use an instrument to look into your ear, but the usual response is a slight tickle. If you have swelling that might be painful, your doctor will avoid touching that area.
Tests for hearing loss also do not expose you to any harmful substances, such as radiation or chemicals. You could take hearing tests every day of your life and not experience any harmful health effects. There is really no reason to resist a hearing test — the result could be an effective treatment for your hearing loss.
What Are the Symptoms of Hearing Loss?
Hearing loss is not usually addressed until it becomes obvious. People suffering from hearing loss usually wait about seven years before they seek help with this deficiency. Hearing loss is incorrectly considered a nuisance by many people, rather than a medical condition to be treated.
Most of the symptoms of hearing loss are fairly obvious, such as:
- Trouble understanding someone on the phone
- Inability to hear a person talking behind you
- Frequently asking people to repeat themselves
- Failing to hear your alarm clock
- Struggling to follow the dialogue at the movies
- Turning the volume on a TV or car stereo higher and higher
- Concerned other people are constantly mumbling
- Difficulty following the conversation with more than one person at a time
- Experiencing discomfort at loud restaurants or parties
Many people begin by finding excuses for these signs of hearing loss. They pretend they can hear the conversation, even when they cannot. They blame their dread of loud places on age or preference, rather than admitting they struggle to hear and understand the people around them. Sometimes, they even claim it’s not a hearing deficit at all, but rather a problem of understanding, like talking with someone who has a thick accent or understanding the mumblings of a young child.
The longer you ignore the symptoms of hearing loss, the more you miss out on in life. Avoiding activities you used to enjoy, or pretending to participate in a conversation you cannot hear properly, means you’re not living the highest quality of life possible. The above symptoms are signs you may have a hearing loss, but they are also an indication that your life could be improved with a proper diagnosis.
There are three types of hearing loss: conductive, sensorineural and mixed. The first step is to identify the source of your hearing loss and how severe it is.
Conductive Hearing Loss
A problem with the physical structures in your ear may result in conductive hearing loss. This means the sound waves are prevented from reaching your inner ear, where they are detected and converted into electrical impulses for your brain to interpret.
Conductive hearing loss can be caused by many of the things your doctor looks for during a physical exam. There could be fluid or wax build-up trapped in your middle ear. You might also have inflammation from an infection or a tumor of some sort growing in your ear. Anything that blocks the air from getting to your inner ear can temporarily or permanently affect your hearing.
There is also a condition known as otosclerosis that can cause conductive hearing loss. It causes the bone in the middle ear to grow abnormally, changing the shape and relationship of the structures and spaces in your ear. As this bone continues to grow, hearing loss can become more severe.
The bones of the middle and inner ear transfer sound through vibration. When these bones are altered in shape or density, they vibrate differently. Otosclerosis causes a thickening of the ear bones in a certain area that restricts their ability to vibrate.
There is much more to learn about otosclerosis, but it is believed to be a genetic condition linked to autoimmunity. It could involve one of several genes, and you have a 50% chance of developing it if one of your parents has it. Most cases are diagnosed between the ages of 10 and 30, but hearing loss can continue to progress.
Depending on the severity of the issue, hearing loss from otosclerosis can be treated with hearing aids or surgery — however, there are forms of this disease for which there is not yet an effective treatment.
Sensorineural Hearing Loss
The hearing loss that many people experience as they age is due to damaged nerves in the inner ear. Sensorineural hearing loss reduces the inner ear’s ability to transmit signals to your brain. You hear the sounds, but cannot figure out what they mean. This is commonly the cause of people complaining about mumbled conversation. The sounds are reaching the inner ear, but the nerves there are not sending all of the electrical impulses to the brain for decoding.
As we age, the nerves in the inner ear wear out. Some die or are damaged from exposure to loud noises. People who work in very loud environments and do not employ proper ear protection tend to suffer from sensorineural hearing loss. The same is true for people who listen to their music too loud or attend loud concerts frequently.
Other causes of sensorineural hearing loss, besides exposure to loud noise, include:
- High fever
- Viral infections
- Certain types of tumors
- Ototoxic drugs
- Meniere’s disease
Ototoxic is the name given to certain medicines that cause hearing loss, either temporarily or permanently. Hearing loss caused by these drugs tends to come on very quickly. It often begins with a dizzy feeling called vertigo and ringing in the ears called tinnitus.
This form of hearing loss usually occurs in older people who take a lot of medicines. Some of the hearing loss will reverse when you stop taking the drugs, but some of it is permanent.
Some common medications that can cause hearing loss include:
This list includes aspirin taken in large doses and anti-inflammatory meds obtained without a prescription and taken often for pain relief. Certain types of antibiotics pose a particular risk to people with kidney disease or those already suffering from hearing loss. Some medications for treating high blood pressure or cancer can also cause hearing loss.
People taking two or more of the medicines on the list above should be monitored regularly for hearing loss. Also, anyone who takes large doses of these drugs or is on them for a long period of time should be aware of potential hearing-related side effects. It’s always a good idea to mention possible hearing loss symptoms to your doctor.
Sensorineural hearing loss is usually permanent, but it can happen in degrees. Although surgery will not replace or repair the damaged nerves, hearing aids can help improve the inner ear function and reduce symptoms. Recognizing the cause of sensorineural hearing loss can also reduce the damage by ending the exposure, if it is noise-related.
Mixed Hearing Loss
A combination of sensorineural and conductive hearing loss is not uncommon. This occurs when the outer and middle ears are damaged or blocked in some way that prevents sound from getting to the inner ear, and there is nerve damage in the inner ear. It is easy to see how each type of hearing loss, created by a different cause, compounds the effects of the other.
If your nerves are not fully transmitting the sound to your brain for interpretation, and those inner ear nerves are not even getting all of the sound, your reduction in useful hearing can be severe. Any treatment that would restore a portion of your lost hearing would improve your quality of life.
Depending on its cause, conductive hearing loss can be easy to remedy. Through medical or surgical means, your doctor might be able to clear the blockage in your ear. Sometimes, regular professional ear cleaning is all that is required to restore your conductive hearing abilities.
Central Hearing Loss
The hearing process begins when air containing sound waves moves into the outer ear. It passes over the structures of the middle ear and is funneled to the inner ear. The nerves of the inner ear change the sound waves into electrical impulses and send them on to the brain. In the brain, complex processing takes place to translate those electrical impulses into the sensation of audible sound.
The hearing process continues in the brain beyond that as you apply meaning to those sounds. Your brain determines whether you’re hearing music or conversation, for example. In the case of conversation, it decodes the words and assigns meaning to create your understanding of what is being said.
There are people who exhibit symptoms of hearing loss, but who do not show any nerve damage or structural blockage. Often, these people are suffering from central hearing loss. They are hearing just fine, but their brains struggle to interpret the meaning of the sounds.
The only treatment for this central nervous system deficiency is to make it easier to “hear” by controlling the environment. People with central hearing loss do better in quick spaces and one-on-one conversations.
Hearing Loss Treatments
Almost anyone with a hearing deficiency can improve their quality of life with some form of treatment. Conductive hearing loss is perhaps the easiest to treat. Most blockages can be removed right in your doctor’s office. Ear wax build-up can be washed away almost instantly by your doctor, even if your home solutions don’t work.
Sometimes, attempting to clean build-up or debris from your ears at home with a cotton swab exacerbates the situation. You could potentially push material farther into your ear, making it even harder to retrieve. There are some ear washes available over-the-counter, but the best solution to an ear blockage that’s causing hearing loss is to see your doctor.
In addition to cleaning out debris, your doctor can assess if there are other physical barriers to your hearing. If a tumor or swelling are the problem, he may need to apply different treatments. A tumor could require surgery to remove. Swelling that is due to infection can be treated with medication. Most treatments for conductive hearing loss are quick and easy.
Hearing loss due to fluid in the ears may take a little more time to resolve. Your doctor can attempt to drain the fluid. If it comes back frequently, he may install tubes in your ears to remove the fluid with a continual means of draining. Children often require ear tubes if they suffer from frequent ear infections. It is not uncommon, however, for older adults to need tubes to drain fluid build-up from their ears.
Of course, if your conductive hearing loss is due to an injury that has changed the shape of your middle ear, the treatment could be more complex. Once the swelling goes down, the extent of the needed repair can be assessed. Surgery is the most likely treatment in the case of injury-induced conductive hearing loss.
Treatment for sensorineural hearing loss centers around reducing the symptoms. We do not yet have an effective way to repair nerves, but we can attempt to replace their functions with other devices. In sensorineural hearing loss, the nerves in the inner ear are no longer transmitting the sounds as electrical impulses to the brain. The death of nerves and receptor cells is the reason for this deficiency.
Hearing aids were developed to solve this problem. They take the place of those nerves and do the job for them. Sensorineural hearing loss cannot be completely replaced with a hearing aid, but the hearing aid can improve your ability to hear and function normally in your everyday life.
Beltone offers an online hearing test to get you started in evaluating your potential hearing loss. This test takes just five minutes, and with headphones it can test the hearing in both of your ears. Take our online test today to find out if you are experiencing any hearing loss. A follow-up visit to your doctor or audiologist could outline treatment options that can improve your comfort and quality of life.