Understanding Selective and Sensorineural Hearing Loss: Causes, Types, and Treatments
Hearing loss affects people of all ages and can be caused by many different factors. Hearing problems don’t discriminate and can affect people at any stage of life.
The three basic categories of hearing loss are sensorineural hearing loss, conductive hearing loss and mixed hearing loss. Hearing testing is critical for discovering exactly what type of hearing loss you have, and will help determine the hearing care solution that is right for you.
Most adults received their last hearing test when they were in grade school. It is a good idea to have your hearing checked when you are an adult at least once during your annual physical.
Sensorineural Hearing Loss (SNHL)
What is sensorineural hearing loss? Sensorineural (sen-suh-ree-NUR-uhl) hearing loss, also known as SNHL, occurs because of damage to your inner ear. That’s because tiny receptors in your inner ear called hair cells are damaged. These hair cells are responsible for converting sound waves into signals that your brain interprets as sound.
This type of hearing loss occurs when the inner ear or the actual hearing nerve itself becomes damaged. It can happen suddenly due to an illness, injury or exposure to loud noise, like an explosion. Alternatively, SNHL can develop gradually over time as part of the aging process. And in some cases, people are born with it.
Sensorineural loss is the most common type of hearing loss. It can be a result of aging, exposure to loud noise, injury, disease, certain drugs or an inherited condition. Unfortunately, these cells can’t repair themselves, making SNHL a permanent condition in most cases. But wearing hearing aids or other hearing devices can greatly improve your hearing and quality of life.
Sudden sensorineural hearing loss may occur very suddenly or over the course of a few days. It is imperative to see an otologist (a doctor specializing in diseases of the ear) immediately.
Types of Sensorineural Hearing Loss
There are a few different types of sensorineural hearing loss:
- Unilateral sensorineural hearing loss affects one ear.
- Bilateral sensorineural hearing loss affects both ears.
- Asymmetrical sensorineural hearing loss affects both ears, but hearing loss is worse in one ear.
- Sudden sensorineural hearing loss is a medical emergency that happens within 72 hours of an injury, illness or exposure to loud noise.
SNHL has a significant impact on your hearing ability. You may not be able to hear soft sounds, and even loud noises may seem muffled.
How Common is Sensorineural Hearing Loss?
Sensorineural hearing loss, particularly the age-related variant, is one of the most common types of hearing loss in adults.
Conductive Hearing Loss
This type of hearing loss occurs in the outer or middle ear where sound waves are not able to carry all the way through to the inner ear. In some people, conductive hearing loss may be reversed through medical or surgical intervention.
Mixed Hearing Loss
Sometimes people can have a combination of both sensorineural and conductive hearing loss.
Understanding Low-Frequency Hearing Loss
Is low-frequency hearing loss different from others? Low-frequency hearing loss compromises the ability to hear noises and sounds classified as low. Essentially, it affects only a specific frequency sound spectrum.
As the disorder develops, it becomes difficult to hear different pitches of sounds. In general, the more severe the hearing impairment, the more difficulty one has in hearing sounds closer to middle frequencies.
| Frequency | Description |
|---|---|
| Low | Compromises the ability to hear low noises and sounds. |
| High (5000-20000 Hz) | Loss of ability to hear birds chirping and women's voices. |
How common is low-frequency hearing loss? According to World Health Organisation estimates, there are approximately 466 million people worldwide who suffer from some type of hearing loss. This number is said to double by 2050.
Given the phenomenon of an ageing population that affects our country, this number has been steadily increasing since 2012, with a greater impact in the male population.
Low frequency hearing loss may be due to a conductive or sensorineural hypoacusis. In the first case, the cause is a disfigurement or damage to the pinna, eardrum or ear bones, or an obstruction of the canal due to mucus or earwax. In the case of sensorineural hearing loss, there is damage to the hair cells within the cochlea or to the nerve pathways in the ear.
This type of hearing loss is generally more severe and is caused by congenital diseases, acoustic trauma, infectious diseases or pathologies such as osteosclerosis and Manière's syndrome, and, more frequently, by presbycusis, the natural degeneration of auditory tissue due to ageing.
In the examples mentioned above, low frequency hearing loss is not an exclusive symptom: there are often other disorders accompanying it that vary in severity, reversibility and time of onset.
For example, if low frequency hearing loss is due to Wolfram syndrome (a rare endocrine disease related to diabetes mellitus), the hearing loss normally manifests itself within the first decade of life, is progressive and irreversible and anticipates the onset of the full-blown disease, which occurs in adulthood.
In the case of Ménière's Disease, which specifically affects the inner ear, hearing loss at low frequencies is a fluctuating symptom. This means it surfaces and disappears sporadically, but over time leads to a progressive deterioration of hearing ability.
It is common, in cases of congenital disease, such as Mondini's dysplasia, which concerns a malformation of the inner ear, for hearing loss to occur early in life. In this case, the hearing loss is irreversible, whether it was severe from the start or whether it worsened over.
If the hearing loss is sudden, there is no typical age of onset, it is difficult to identify the exact cause. Hearing loss occurs within 24-72 hours of head trauma, severe stress or infection, among other causes. The chance of full recovery in this case is 25%.
Generally speaking, cases of sensorineural hearing loss are the most severe, profound and irreversible, because they are caused by inner ear cell and tissue damage, particularly to the cochlea. It is precisely as a result of the work of the cochlea that our body translates vibrations into nerve signals for our brain.
However, an early diagnosis can provide effective treatments for symptoms, including low-frequency hearing loss, and the diseases that cause them.
Symptoms of Low-Frequency Hearing Loss
Symptoms of low-frequency hearing loss are not always easy to detect, particularly due to the fact that, in the mildest and most progressive forms, the person suffering from hearing loss can carry on conversations and sufficiently hear sounds in their surrounding environment.
Following conversations attentively requires more effort than normal, especially if one is in a group and in environments where background noise is very present.
Speaking on the telephone can be tricky as it can be very difficult to distinguish words, especially if there is background noise and even slight line disturbances. You may ask the person on the other end of the line to repeat himself many times.
Male voices and deeper sounds are often garbled and may be difficult to distinguish and interpret.
Other symptoms include:
- Tinnitus, i.e. a whistling sound that is perceived even in the absence of sound.
- Ménière's disease.
Diagnosing and Treating Low-Frequency Hearing Loss
In order to diagnose low-frequency hearing loss, it is necessary to undergo a hearing test conducted by a professional. Tests during this early stage are used to establish the quality of sounds that the patient can perceive and can be trusted in the diagnosis of a hearing impairment. In that case, further checks are recommended to establish the root cause of the symptoms.
Treating low-frequency hearing loss effectively requires a clear understanding of its causes. Sensorineural hearing loss often requires pharmacological treatment, particularly during its acute phase.
Modern hearing aids use technology that is able to enhance the auditory perception of missing frequencies while also filtering out background noise and making sounds clearer. In the case of low-frequency hearing loss, a hearing aid treatment succeeds in ensuring a higher quality of life.
For many patients, a partial hearing loss means a total decrease in quality of life: an experienced hearing aid specialist will be able to recommend the right solution to effectively solve any specific hearing problems.
Hearing implants are for all intents and purposes a part of our body as their proper functioning makes us the people we are.
Hearing aids can be tested free of charge for the first 14 days to give patients time to understand and find the hearing aid that is right for them.
What is Selective Hearing?
You’re probably familiar with the phrase “selective hearing” in reference to people only hearing what they want to hear. While it’s often used in a joking sense, selective hearing is an experience that researchers are only just starting to understand.
Selective hearing is the ability to listen to a single speaker while in a crowded or loud environment. You might also hear it referred to as “selective auditory attention” or the “cocktail party effect.”
Selective hearing involves many factors, including your goals, vision, and brain activity patterns.
Factors Influencing Selective Hearing
Goals
Your brain chooses what to listen to based on what you’re trying to do. For example, imagine that someone started talking to you while you were trying to finish watching an episode of a TV show. Chances are good that you didn’t hear much of what they said to you. Your brain prioritized the sound of the TV over that person’s voice because your goal was to finish watching the show.
A 2008 study put this concept to the test by asking participants to pay attention to sounds in one ear but not in the other. The investigators then played different pitches in each ear at the same time and asked the participants to note any changes in pitch in the ear they were asked to focus on.
MRI scans of the participants’ brains showed that they heard the sounds in each ear. However, when they were detecting changes in the specified ear, they ignored the sound in the other ear.
Vision
Visual cues are also an important part of selective hearing. For example, a 2013 study involved playing audio of a man and woman talking at the same time. Participants were asked to pay attention to either the female or the male speaker. They had a much easier time focusing on only the male or the female voice when watching a video of the speakers along with the audio.
Based on these results, being able to see someone while they’re talking might help you listen more effectively.
Brain Activity
A 2012 study found that the presentation of sounds within your brain doesn’t reflect all of the sounds in your environment but, rather, what you want or need to hear. These results are similar to those of the 2008 study discussed above.
However, the investigators also found that they could use the patterns of brain activity they observed to predict which speaker or words someone was listening to.
Investigators used about 90 electrodes per person to monitor the brain activity of people undergoing surgery for epilepsy. Participants were asked to listen to two different samples of speech at the same time. Each sample contained a different speaker and phrase. They were then asked to pick out which words were said by one of the two speakers.
Using information about brain activity patterns from the electrodes as well as a decoding process, the investigators reconstructed what the participants heard. The brain activity patterns suggested that the participants only paid attention to the speaker they were asked to focus on.
In addition, the investigators were able to use these brain activity patterns to predict which speaker the participant listened to and determine whether they paid attention to the wrong speaker at any point.
Real-World Applications of Selective Hearing Research
While the recent research surrounding selective hearing is interesting, it also has several real-world applications.
The predictive and decoding technology from the 2012 study discussed above may help researchers better understand the effects of aging and certain conditions on hearing function.
In addition, people with hearing loss, ADHD, auditory processing deficits, and autism seem to have trouble with selective hearing. The decoding technology could help researchers understand what people with these conditions are actually hearing and processing.
Knowing this information could be crucial for developing new treatments.
Improving Your Listening Skills
Some people seek out treatment for selective hearing. However, it’s a phenomenon that affects nearly everyone. There are a few things you can do to improve your listening skills, such as:
- Pay attention. When you’re talking to someone, try to pay attention to more than just their words. Try to take in visual cues from their facial expressions or body language while they’re talking.
- Summarize. At the end of a conversation, try briefly summarizing the main points to make sure you clearly understood everything.
- Ask questions. Don’t be afraid to ask the other person a question about something they’ve said that’s unclear. Taking a few seconds to ask them to elaborate is usually less bothersome than a potential misunderstanding down the line.
- Mind your own biases. While it’s easier said than done, try to be aware of your own biases and judgments about people when you’re talking to them.
When to See a Specialist
Low-frequency hearing loss is less common than high-frequency hearing loss, which is why it is important to carefully monitor the symptoms, even if they do not seem to be anything to worry about.