All About Hearing Loss – Episode 5
Let’s talk about hearing loss. What types of hearing loss are there? What does it mean you have a conductive hearing loss or a sensorineural hearing loss? What are the levels of hearing loss, from mild to moderate to profound? Listen to this week’s episode to learn all about hearing loss.
Welcome back to the All About Audiology, a podcast that’s well, all about audiology. I’m your host Dr. Lilach Saperstein, an audiologist so passionate about this field. In our last full episode we spoke about how hearing works, all the complex and fascinating structures and how they all work together- we spoke about so much and yet we only just scratched the surface of how the different parts of our auditory system work together so that we can hear.
Today, we’re going to talk ALL ABOUT HEARING LOSS. What happens when some parts of that system aren’t working in the typical way, or if pieces are missing and so on.
We’ll be diving into the different kinds of hearing loss, what’s meant by different levels of hearing loss, AND, we’ll also touch on many different causes of hearing loss.
Just before we begin, I want to remind you that I’m interested in hearing your comments, answering any questions you have and that the All About You episodes, every other episode, are all about you and your experience with audiology, so please feel free to contact me on the website, allaboutaudiology.com, or send me a direct message on instagram- @allaboutaudiologypodcast, and of course we have our Facebook group, Allaboutaudiology!
So let’s dive in to today’s topic:
There are two major categories or types of hearing loss, well actually three. There’s conductive hearing loss, sensorineural hearing loss, and there’s mixed hearing loss which is when a person has components of both conductive and sensorineural. So two, but really three if a person has a combination of the first two. To review from last week, we have an outer ear, middle ear, and inner ear.
When there’s a problem with the outer or middle ear, this can lead to a conductive hearing loss, because sounds are not being conducted properly into the inner ear where the cochlea is. So some causes of this kind of hearing loss, of conductive hearing loss, will have to do with anything that’s blocking sounds from getting into the ear canal, like impacted wax, or any kind of issue with the the ear canal itself, like swimmer’s/surfer’s ear, where bony growths can form along the ear canal and eventually block the ear canal.
Causes can be congenital, from birth, like atresia, microtia, or anotia, that these are different malformations of the ear and ear canal. Anotia is having no outer ear, microtia, is when the outer ear is very small, and atresia of the ear canal is a narrowing of the ear canal and there can be stenosis of the ear canal, where the skin is actually blocking. These are different outer ear causes of conductive hearing loss.
There can also be middle ear causes, and here again these can also be present from birth, like malformations of the ossicles, or missing ossicles, or a problem with the bones in the body overall- these could all contribute to a conductive hearing loss and sounds are not being conducted in. There are also acquired issues that can happen throughout the lifespan, things like fluid accumulation in the middle ear space, a perforated ear drum (a hole in the ear drum), ear infections, and chronic ear infections that lead to cholesteatoma, and this is another kind of growth, but in the middle ear space which can then erode the ossicles. Another thing that can happen is something called otosclerosis, which is fixation of the ossicles, when the stapes isn’t moving properly then, again the sounds are not being properly conducted in.
In general, with the things that can cause conductive hearing loss that I just gave you a couple of examples of, there may be a medical or surgical treatment option available. It’s not necessarily permanent the way that sensorineural hearing loss is, there might be an option. This of course, is a generalization. And if you or someone you know or love is dealing with these issues, it’s extremely tough, often very painful, and a lengthy journey, we’re talking about surgeries! And even if there might be an option, there’s no guarantees, and sometimes people aren’t candidates.
I hope you’ll write in to share your journey with me and other listeners dealing with the same thing so we can not only connect, but learn from one another. With conductive hearing loss, you’ll likely be referred to an ENT, ear nose and throat doctor to discuss your treatment options, and of course you’ll be seeing an audiologist for your diagnostic testing.
People with conductive hearing loss are generally excellent candidates for hearing aids because the problem with the conductive hearing loss is usually a problem of volume. The sounds are not getting conducted in but the inner ear is working properly then the problem is actually not with hearing, it’s getting sounds in to our organ of hearing. So if the hearing aid device is able to provide the extra amplification, making sounds louder, then a person will generally have good understanding and benefit a lot from using a hearing aid.
This is in contrast to the second type of hearing loss which corresponds to damage in the inner ear and of the nerve, the kind of hearing loss that’s called sensorineural hearing loss, referring to the sensory cells in the cochlea and the eighth nerve. (Definitely go back to episode 3 to learn more about the different parts of our ear and the cochlea!) When there’s damage to the cochlear hair cells, or other parts of the inner ear, it’s almost always permanent and currently irreversible- here’s hoping on that research! Mammalian hair cells do not regenerate but those of fish, birds and amphibians do, so there’s research going on hoping to translate those mechanisms to humans, but as it stands sensorineural hearing loss is permanent. This kind of hearing loss can be present at birth, from some sort of structural malformation or from genetic causes that affect the development of structures in the inner ear in utero. Sometimes there is a syndrome that affects multiple body systems or different senses, and that’s the underlying cause of not only hearing loss but other things.
Another cause of sensorineural hearing loss could be acoustic trauma, which basically means a blast or a really loud noise that causes damage to the hair cells, this can be like an explosion or a gunshot, but can also be excessive noise exposure over time, like working with machinery, or at very loud music venues. Noise induced hearing loss is one of those things that audiologists focus on a lot because there’s a way to prevent it by minimizing your exposure dose. When we talk about noise exposure we have to discuss it in terms of dose. The dose is not only how loud the exposure noise is but also for how long. So if you can reduce how loud the sounds are, by using hearing protection (like ear plugs or ear muffs), and reduce the length of the exposure then you can reduce the risk.
Sensorineural hearing loss is also associated with the natural wear and tear of the body leading to presbycusis, which means hearing loss associated with aging. With sensorineural hearing loss, it’s really variable how someone will do with hearing aids, because it’s not only a degradation of the hearing ability in terms of volume, but there’s often a distortion of clarity that accompanies sensorineural hearing loss. This doesn’t mean that people with sensorineural hearing loss are not candidates for hearing aids, they definitely are and can benefit a lot from having a hearing aid. But it might help to explain why the hearing aid is not a solution to all hearing problems. It’s actually not fixing what’s wrong, it’s an aid. A person can get a lot of benefit from the hearing aid and understanding what kind of hearing loss a person has, plays a big role in how they are going to do with hearing aids.
Now, we talked about conductive and sensorineural hearing loss. The third type of hearing loss is called Mixed, when there are components of both types, both conductive and sensorineural. Okay, now let’s talk about Configuration. Which kinds of sounds can a person hear or not. Humans are able to hear from 20 Hz all the way to 20,000 Hz- this means we can hear very low pitch, rumbly, sounds like the bass and we can also hear very high frequency sounds that have a high pitch like string instruments or a piccolo, a flute, or a bird. So within this range is the range of speech, between about 250- 8000 Hz- and those are the frequencies that are tested in a regular hearing test, and charted onto a graph called an audiogram. You can think of it like the keys across a piano, low pitches on the left, going to higher and higher pitches on the right. So when you go in for a test, you’ll hear low pitch sounds and high pitch sounds and you’ll have to raise your hand every time you hear it.
In speech, we have lower pitched sounds that are the vowels, like aaa, uuu, and also some consonants like ‘m’ and ‘l’, and we have much higher pitch sounds that make up the consonants, like ‘t’ and ‘f’ and a very problematic one ‘s’ because these sounds are the ones that carry a lot of linguistic meaning. Think of how important it is for you to hear the letter ‘s’ and then you know if something is plural or not. You can know if a person is using a possessive apostrophe s or third person singular (he eats, she eats). In speech, those high frequency consonants carry a lot of meaning.
Another way to think about this is with looking at the speech banana. Did I say speech banana? Yes I did! This is an image- google it! – that shows you on the audiogram, the graph of the different pitches and volumes where the different sounds of speech and different letters, fall along the frequency spectrum, and it kind of makes the shape of a banana. And what you can do is graph out a person’s hearing loss results, their audiogram, on top of the speech banana and see which sounds they will have trouble hearing.
We have to discuss what are the different levels of hearing loss. When we test for your thresholds, that means how loud does the sound have to be for you to hear it, or another way of saying that is what’s the softest volume you could hear for a particular sound, we make the sounds softer and louder, going softer than you can hear, and then slowly raising and raising the volume until you respond, and then going down again and back up again a few times until we get an accurate threshold. And we do this testing method for all the sounds across the frequencies that we are testing. Loudness or volume is measured in decibels, the dB scale and on the audiogram, this is going down which means it’s getting louder and louder. And if someone can hear very soft sounds, like rustling of leaves, their responses are going to be at the top of the graph. Whispering is about 10/15 dB. Normal speech conversation is about 50 dB, and someone yelling is about 75 dB/ and an airplane is maybe 100 dB. Sometimes you go to rock concerts and it’s 115 dB or something really, really loud. And I’ll tell you that the dB scale is actually logorothmic, so it gets exponentially louder the higher the dB is. But back to our audiogram, the dB scale is graphed in such a way that the lower down on the graph you go, the more hearing loss there is, the louder sounds had to be for a person to hear them. At the top is the normal range of hearing- up to 20/25, and then mild hearing loss, moderate, moderately severe, severe and profound. The lower on the audiogram, the higher the level of the hearing loss.
And you can start to see why we can’t give a percentage of hearing loss in a simple way- you have to know the type of hearing loss, conductive, sensorineural or mixed, the degree of hearing loss, mild to profound, and you have to understand that the configuration might be different for different frequencies. It might be flat, that means that there is the same level of hearing loss across all the frequencies, but it might be sloping to a hearing loss that’s worse in the higher frequencies, which is very common. Presbycusis often presents as a high frequency hearing loss. As we age, the hearing of the higher frequencies degrades first and then the clarity of speech becomes very difficult. And this is why one of the most common complaints of people with hearing loss is that they can hear but they can’t understand. They know that you are speaking with them but they can’t make out the words or the meaning and this is extremely common with high frequency hearing loss or a sloping hearing loss.
I hope this episode was helpful for you and I’m so glad you joined me for this episode “All About Hearing”. Thanks so much for being a listener and supporter of the All About Audiology podcast. I’d love to hear from you and hear what learned today and what’s been your experience with audiology. Have you had your hearing tested? Does this information help you understand the audiogram of your family member who had their hearing tested? Let me know where this lands for you.
I’ll be happy to read your comments, questions or feedback, send me an email, a direct message on Instagram, or a review on iTunes and it might be there in the next mini episode that will be all about your comments and your experience with audiology.
I’m Dr. Lilach Saprestein and you’ve been listening to All About Audiology.