Introduction to Hearing Loss SUSAN BASHINSKI: SLIDE 1 Hello, my name is Susan Bashinski. Welcome to this webinar, in which we will talk about a brief introduction to hearing loss, types of hearing impairment, elements of hearing impairments-- just try to give an overview of how hearing loss is in learners with children who have labels of deaf-blindness-- how their hearing losses might be described. SLIDE 2 As we categorize hearing loss, there are four major types of losses we'll be taking a look at today. I think some of these will be very familiar to many of you. One or two of them might be a new way of looking at hearing impairments. We'll talk about conductive hearing losses, sensorineural hearing losses, processing problems, or what is called CAPD-- I'll keep you guessing on that one for a couple of minutes-- and then combination problems, because these different types of loss may and often do occur simultaneously with one particular learner. SLIDE 3 So let's begin by taking a look at conductive hearing losses. A conductive hearing loss occurs when sound cannot effectively pass from the outer ear to the inner ear. Sounds pretty simplistic, but that's really what's involved. Sound can't get from outside the learner's body through his outer ear, middle ear, and get into his inner ear. And this could be due to a very large number of reasons why. I've cited three of the most common. Number 1, in some kids who have labels of deaf-blindness, the auditory canal itself is malformed or underdeveloped. I worked with one little fella in the state of Kansas who simply did not have any auditory canals at all. So a malformation in that part of the ear may yield a conductive loss. There may be a blockage in the external ear by either too much wax buildup, fluid in the ear, a tumor in the ear, anything that would block the sound waves moving from outside the learner's body to his inner ear. The third reason is one that I think most of you will have considered, will have experienced at some point in time, and that is otitis media. Those are the big words for saying, oh, a middle ear infection. Yes, a middle ear infection is a common cause of conductive hearing loss because fluid builds up in the middle ear. And when that fluid is there in the middle portion of the ear, it prevents sound being reliably conducted from outside the learner's body to the learner's inner ear, where all of the magic really happens. So that fluid buildup is just like, when you're under water, sound is processed very differently. You can hear things, but it's distorted. It's not clear. It's not crisp. And that's not exactly what happens with a middle ear infection, but I think it's the closest thing we can come to maybe understanding a little bit of what goes on. SLIDE 4 Conductive hearing loss attenuates the sound. And what that means is it actually weakens the sound signal. A conductive hearing loss weakens the strength of the sound waves, because the ear drum and the middle ear-- because the ear drum in the middle ear does not move like it's supposed to, when it's backed up with fluid or when the wax prevents the sound waves from reaching it-- and the strength of which they're sent. So a conductive loss weakens the sound. SLIDE 5 Let's take a look now and compare this to a sensorineural loss. A sensorineural loss is caused by poor development of, or damage to, the inner ear-- just generally, the cochlea. That may be a familiar word, if you've heard of the cochlear implant. The inner ear is the cochlea. So a sensorineural loss is caused by poor development or damage to the cochlea and/or the auditory nerve. The eighth cranial nerve is the auditory nerve. One or both of those are damaged or poorly developed. Particularly in learners with deaf-blindness who have CHARGE syndrome, and this is a fairly significant proportion of the population of kids with deaf-blindness, one of their primary identifying characteristics is now development of their ears, both externally, but internally. The cochleas of many kids with CHARGE syndrome are spongy, malformed. They only have 1 or 1 and 1/2 rotations. It's like the part of the ear that's like the snail shell. Lots of unusual things occur with the cochleas of kids with CHARGE syndrome. The second thing that's important to realize, which is why children's health programs try to be diligent about supporting families in regard to treating ear infections, chronic otitis media or chronic middle ear infection-- to use the more common, comfortable language-- may cause permanent damage to the ear. And if chronic middle ear infections cause that damage, it can result in a sensorineural hearing loss. So a middle ear infection initially only causes a conductive loss. When that fluids build up, the sound doesn't get through the fluid and get to the eardrum with the strength and clarity it should. But if it's left untreated, it goes on chronically for several months, years, it can result, often does result, in a sensorineural hearing loss. The importance about this, a sensorineural loss is permanent. And we'll look at that. SLIDE 6 There is one other aspect of sensorineural hearing loss, and this is one of the most recent areas of development. Medical science is doing some fascinating research in regard to auditory dyssynchrony. Or Auditory Neuropathy, AN, that may be a term some of you have heard before. If you've heard it, I'm guessing you've heard it only recently. But if there are abnormalities in the brain stem or the auditory cortex of the brain, those abnormalities can result in a condition that is casually referred to as AN or auditory neuropathy. In the literature, you sometimes see this written as auditory neuropathy spectrum disorder. But as I was preparing this information for today, it seems that the preferred term in the field of audiology and speech language pathology is called this abnormality in the auditory cortex or the brain stem. So I used the term in red on your PowerPoint to talk about it, and that is auditory dyssynchrony. SLIDE 7 So we looked at how conductive hearing losses affect the sound. Let's look at how a sensorineural hearing loss affects the sound. It too attenuates or weakens the sound signal coming from outside the child's body. But it does so much more than that. Sensorineural hearing loss also distorts the perception of sound, because something about neurological system that supports and processes it is damaged or malformed. So it's distorted, not only weakened. And as I mentioned before, a sensorineural hearing loss is permanent. You're not going to correct it. You're not going to treat it with hearing aids or find treatment through an FM system in a classroom. Sensorineural loss is permanent. The only kind of treatment, if you will, that can address a sensorineural hearing loss is that a learner would get a cochlear implant, which is a totally separate kind of major surgical procedure. SLIDE 8 When you talk about conductive hearing losses, sensorineural hearing losses, in all the books we use to teach special education teachers, there is a third category that's called mixed. We have to love that, right? But it's one of those straightforward, literal types of terms that can be very important as we work with learners with deaf-blindness to try to build appropriate listening environments, build appropriate acoustic environments for them, work and target their communication skills. And if a child's records show that she has a mixed hearing loss, that means the loss she has is both a conductive hearing loss and a sensorineural hearing loss. And it is not uncommon that kids with deaf-blindness will have a mixed loss. SLIDE 9 So let's shift gears a little bit and talk about a second type of categorization system that is used to describe hearing loss. Hearing loss, as you see on the screen, can be described as either unilateral or bilateral. These terms can be combined with the previously-defined terms. You could have a unilateral conductive hearing loss, or a unilateral sensorineural hearing loss, or a bilateral sensorineural hearing loss. So these terms-- unilateral, bilateral-- talk about how many ears are involved. Previous terms talk about the type of hearing loss in conjunction with the anatomy and physiology of the learner's body. So they can be combined in any number of different ways. If you say a learner has a unilateral loss, that means that she has, essentially, normal hearing in one ear and a hearing loss of any degree in the other. Could be a mild hearing loss. It could be a profound hearing loss, but it's limited to one ear. The child experience is essentially normal hearing in the other. When we use the term bilateral, the hearing loss occurs in both ears, though the intensity and frequency of the losses ear to ear may be the same, or they may be different. In a few minutes, we're going to look at, what does it mean by intensity? What does it mean by frequency? For now, let's leave it to say in a bilateral loss, the learner does experience some hearing impairment in each ear, but the nature of the loss, the degree of the loss, the range of sounds she might be able to process through each ear-- they might be identical, but more than likely they're going to be different. SLIDE 10 So let's talk about the third major category of hearing impairment from our initial slide. This is central auditory processing disorder. There's the meaning of CAPD. It's another acronym. Stands for central auditory processing disorder. This type of a hearing impairment is somewhat analogous to CVI, for cortical vision impairment if you've heard that term. I think CVI is a much more commonly used term than CAPD. Cortical vision impairment has received a lot of attention for many, many more years in special education than has CAPD, so I just use that reference to say if you're familiar with CVI, central auditory processing disorder is the complement for the hearing system. A learner with CAPD will have limited or inconsistent hearing, full quote, due to a problem in the cortex of the brain or the auditory pathways in the brain that do not properly process auditory stimuli. The anatomy of the ear, all three parts, the outer ear, the middle ear, and the inner ear, the anatomy of the ear is not impaired. Outer ear, middle ear, and inner ear all seem to be formed correctly. The ear drum moves correctly. There's not wax build up. There's not fluid. The sound seems to be received, processed, transmitted into electrical impulses. All of that works right, if you'll allow me to say so in such a crude fashion. But when that information gets to the brain, or as it's being transmitted to the brain through the auditory nerve, something doesn't work just the way it should. We do hear with our brains. We don't hear with our ears. Our ears transmit sound. And something about the way the sound is carried in the auditory pathways or is translated by the auditory cortex in the brain doesn't work in typical ways and so the hearing seems to be inconsistent. SLIDE 11 Kids who have a diagnosis of central auditory processing disorder will show difficulties or consistencies with five primary subsets of skills. The first three appear on this slide. The next two appear on the next slide-- or the final two appear on the next slide. Before we talk about these briefly, let me just remind you that not necessarily does every learner who experiences central auditory processing disorder-- not every learner will show difficulties with all five of these subsets of skills. Most learners will show some inconsistencies with most of them. The first is sound localization. This could manifest itself as just an inability to lateralize sound, to know which side of the learner's body the sound comes from. Sound localization is involved when a learner turns toward the source of a sound, looks toward the source of a sound, orients his body toward the source of the sound from side to side front to back. Kids with CAPD may have problems with this. Number two is auditory discrimination. I think this is pretty straightforward just to be able to tell if isolated sounds are the same or different, spoken words are the same or different. It may be for a learner with a blindness who's higher functioning, you're talking about rhyming words. Maybe your kid loves limericks and jingles and loves rhyming words so you're talking about rhyming words. So maybe one day you'll say hat and cap. Do those words rhyme? And the learner will say, yes, they rhyme. And you know all about rhyme or they'll hit a switch to tell you they rhyme or whatever the learner does and they're all over it. They just clearly understand. And then two days later you're talking about hat, and bat, and cat, and do those rhyme and the learner is unable to answer. Those kinds of encounters are very frustrating for families and very frustrating teachers because the performance is so inconsistent. But with learners who experience CAPD, that may be responsible because those sounds just don't get transmitted reliably from day to day or even hour to hour. A third subset of skills that is affected by CAPD is the processing of quick sound sequences, patterns of sound, even if it's not spoken sounds. To clap your hands-- maybe you clap two times and you want the learner to clap two times back or one, two, three, [CLAPPING] and clap. And sometimes kids will be able to do it and sometimes they will not. It's that inconsistency in the way the sounds are transmitted with CAPD-- transmitted process. I'm sorry. It's the processing piece that's the problem. SLIDE 12 The fourth and fifth sets of skills impacted by Central Auditory Processing Disorder-- number 4, weakening of auditory skills in conditions with competing speech or background noise. This one is exceptionally common. One of the most common in my experience and professional opinion, along with number 1-- the localization of sound. If you are in noisy conditions-- if you're in a restaurant as opposed to the quiet of the kitchen in your own home, or if you're in the family room or game room of your own home as opposed to in the child's bedroom, or if you're outside on an exceptionally windy day near a lot of traffic-- there's competing background noise. If you're in a classroom of preschoolers where lots of kids are talking, if you're in a computer lab in a high school where they're not using headphones with their computers so there's a lot of computer-generated speech-- situations, conditions in which there is a lot of competing noise or speech, children with CAPD will have a really hard time sorting out the speech to which they're supposed to attend. If you, as a teacher, are trying to talk to the learner in a noisy environment, it's going to be really hard for her to sort out what you are telling her to do, what you are asking her to give you, if there's too much competing auditory stimuli. And the final category is somewhat related to this. You'll see a weakening of auditory skills in conditions when signals are degraded for some reason. Reminds me-- we don't have the technology anymore, but if you would have a record-- a vinyl record-- and it would be played so many times that it starts to sound gritty or scratchy. If you have a poor radio connection in the car when you're starting to drive out of range of a particular favorite radio station, if you have a poor telephone connection-- that's a degraded signal. It's a degraded auditory signal. You just don't have good quality signal. Kids with CAPD will struggle to be able to process those auditory signals. It's very, very difficult for them. It's difficult for us when our neurological systems process sound well. So when you have a system that's inconsistent in how it processes sound, I think it makes logical sense for you to understand why these number 4 and number 5 skill sets are very, very challenging for children, teenagers who have Central Auditory Processing Disorder. SLIDE 13 And then the last one that appeared on our list is combination problem. Kids may show some actual neurological hearing loss-- a conductive hearing loss-- and also have CAPD. Maybe bilateral, maybe unilateral-- it's just, we can have these conditions-- types of losses that we've talked about to this point in time. They may occur in any number of combinations. That's just what makes it interesting and challenging, all at the same time. SLIDE 14 There is one more area that we want to talk about before we finish up with this discussion of hearing loss. This is the part that usually is most confusing to most teachers. I think it's most confusing to many families. And I will say straight up that if there is an audiologist listening to me at this point in time, I apologize for the simplicity with which I'm going to present the dimensions of hearing loss and audiograms. I don't think that the way I will explain this misrepresents these concepts. I think that I'm being true to what the constructs mean, but I am truly trying to simplify them for those of us who don't have formal training in audiology. It's tricky, because if you have listened to the [INAUDIBLE] Deaf-Blind webinar on categorization of vision loss, that seems pretty straightforward. You can talk about how well a person sees from what distance. You can talk about the field of vision through which a person sees. And it's not a multi-dimensional kind of ability or kind of loss. With hearing, that's not the case. With hearing, when we talk about loss, we have to talk about what a person can or cannot hear according to two separate dimensions, and we can't separate them. We have to consider the dimensions of intensity or loudness and frequency or pitch all at the same time. So the way these are set up-- if you've seen an audiogram, there's an x and y-axis, and intensity is on one axis. Frequency is on the other. And sounds-- whether they're environmental sounds, jet airplanes, sirens, lawn mowers, dog barking, or human speech-- the 44 sounds of our English language-- they are scattered across this range of intensity and frequency. And every sound-- every speech sound, every environmental sound-- has both an intensity and a frequency. So we have to talk about loss in regard to each of those dimensions at the same time, and we can't tear them apart. SLIDE 15 So what we're going to do, is we're going to define an audiogram. That's the visual-- that's the graph that describes a particular learner's hearing sensitivity, both in terms of intensity, and frequency. SLIDE 16 And this is what one looks like. This is an audiogram that shows what would be considered a moderate hearing loss. That's where you get this dip off to the right. In the high frequencies you see across the bottom, it says frequency in Hertz-- high. 2,000, 4,000, 8,000-- those are really high frequencies. But you have to talk about the decibels on the up and down, or the y-axis, and the frequencies in Hertz across the x-axis, or the horizontal axis. If you ever see an audiogram, the symbols at the top here that are used to depict the thresholds-- the 0, or the circle for the right ear, and the X for the left ear-- that's pretty standard. Also, in many places, you'll see the circle-- the right ear-- being marked in red, and the X for the left ear being marked in blue. Again, that standard is just for the purposes of transferability so that whoever does the audiogram, whoever reads the audiogram, whoever encounters the audiogram of a particular learner will interpret it the same way. The other thing that I'll point out-- this type of an audiogram is used to provide a visual representation of air conduction. So this is how it's connected. That word, conduction, is connected to what we talked about earlier in regard to conductive hearing losses. These are depictions of conductive hearing losses. It's the kind of picture that will result after there's a hearing test in a soundproof booth, and that kind of thing. So one more time-- the intensity, or the loudness, appears in these numbers 0, 10, 20-- all the way to 110-- down the vertical axis. Those are measured in decibels, written in lowercase d, uppercase B. Across the horizontal or the x-axis is the frequency of the sound-- how closely spaced the sound waves are to one another, how wide sound waves are-- from 125, all the way across to the right, to 8,000. The higher sounding sounds-- the higher notes on a piano, the higher sounds in human speech in English-- have the higher frequencies. The low sounds have the lower numbers. SLIDE 17 So let's take a look at how we might classify hearing losses. For the sake of this webinar, I've chosen to include five different levels. This, again, is an arbitrary classification. Some different audiologists who write in this area will have six. Some will say seven. The general ranges are the same, it's just whether or not one particular range might be split. You have something like this mild to moderate intermediate category in here. These are five that I see as fairly standard in much of the literature, which is why I've chosen to include these for you. So when we're talking about the intensity of a person's hearing, or the loudness-- the intensity or loudness of a person's hearing loss-- we can talk about them in these words of saying mild, a mild to moderate loss, a moderate loss, a severe loss, or a profound loss. To the right of each of these words, I've given you the quantified ranges of sound that the individual can hear. If a person has a mild hearing loss, that person can hear sounds that are 26 to 40 decibels or louder. Mild to moderate loss-- that individual can hear sounds that are 41 to 55 decibels or louder. Moderate-- 56 to 70 or louder. SLIDE 16 Let's go back for just a minute and look at the audiogram. In this particular depiction of an individual's hearing ability, the low-frequency sounds-- the individual could hear those low frequency sounds anywhere from 10 to approximately 18 decibels or louder. That's the top part of the audiogram. The numbers range between 10 and 20, or louder. The sounds get louder as you go down that vertical axis on the left. But over here in those high sounds, those high-frequency sounds, there is a loss anywhere from 45 to 65. So those sounds are going to have to be much, much louder in the high frequencies. And the individual will only have hearing ability of 45 to 65, or louder, which is down the graph, down the audiogram in the high-frequency sounds. So we've got two different things going on here in this particular audiogram. That is not uncommon. The loss in the low frequencies is really pretty mild. Some people would say it's even borderline. It's not a true loss. But the loss up here in the high frequency sounds would be in the moderate range, primarily. Essentially, borderline or no loss, low frequencies. Moderate, in the high-frequency loss. And as I say, some people would say there's no hearing loss here at all. Some people would say slight. But in the chart that I've provided for you here, I didn't even list slight. I went ahead to mild. So it is complicated, and I realize that. But it's just difficult to try to explain hearing loss when it is these two dimensions. SLIDE 18 The frequency is the pitch. It has to do with the size of the sound waves. Hearing ability is indicated by the point of intensity at which an individual can just barely hear a sound at a specific frequency. So if the person can even sort of barely hearing it, quote, it counts. As you went across, the lower numbers-- the smaller numbers are the low frequency sounds. The higher numbers are the high frequency sounds. One more thing I want to say. I want to back up to say one more thing. Wherever the line is drawn on a person's audiogram, that individual is able to process or hear-- that individual hears the sounds at those frequencies and intensities that appear below the line. So the further down the graph, the further down the audiogram the line appears, the less that individual is able to hear-- less frequency, less intensity. The further down, the harder it is that-- the more substantial that person's hearing loss is. SLIDE 19 The very last thing we want to say about hearing impairment for today is just to call attention in the larger sense-- we talked about this with CAP. But we need to call attention to the notion of sound to noise ratio. Because hearing-- everybody's hearing-- is also affected by the presence of background noise in the environment. I know with myself, if I'm in a classroom with lots of college students and they're rustling around, and they're talking to each other, and somebody in the back asks me a question, more often than not I have to say, "can you repeat that for me?" Because there's so much noise in the classroom, I can't hear as well. I think the stereotype's in preschool classrooms-- it's harder for the adults to talk to each other because the little kids are making a lot of noise. Learning is fun, and learning is noisy. So for all of us, even who have intact, typically functioning hearing systems, the presence of background noise, whether it's environmental noise or other speech, really does affect how we hear. The human voice has limited power. And there's a lot of things in our environment that make noise. There's a lot of ambient noise sources. Like fixtures-- and you ever been in a room where the light fixtures buzz and you can't tune it out? Heating ducts, air conditioning ducts, ventilation systems, computers, if you're on exterior walls of a school where outside noise could filter in-- all of those things create noise. Sound is what we refer to as like-- the teacher directives, other student responses-- the language of learning is the sound or the sounds produced by noise makers, music, animals, to which the learning is supposed to attend. Noise it is all the background stuff, student-generated noise or environmentally-generated noise. And there is a lot of guidelines as to what sound-to-noise ratio should be for children, teenagers, adults with different levels of hearing loss. Secondly, how far a learner is from the source of the sound also affects hearing. Because the human voice has limited power. But the intensity, the loudness of our speech, really decreases as we get further and further away from one another. It's much easier to hear somebody whose sitting across the table three feet away from them than when we're standing across a room 13 feet away from them. And that's just because our human voice degrades as we put distance between ourselves and our communication partners. So those are just things to remember-- sound-to-noise ratio and distance from the child. With a child with deaf-blindness, you might really need to work in quieter environments. You might need to do things to acoustically control or acoustically limit the "noise" in the learner's environment to create an auditory environment conducive to learning. You might have to be nearly on top of the child to really speak directly into his or her better ear to reduce the distance that's set up between you and the learner to whom you're trying to speak if you're trying to help their child learn to process auditory information. SLIDE 20 Finally, the last thing that I want to mention to you-- this is a resource that is a wonderful resource available through the Kansas Deaf-Blind Project. They have it in their lending library. If you're not familiar with this resource, I would encourage you to check it out, borrow it, and play with it. It's Sensory Perspectives, which is produced by SKI-HI Institute at Utah State University. This is a two-CD set that allows you to play simulations of what bilateral moderate hearing loss might sound like, what a unilateral severe profound loss might sound like in noisy conditions. You can set those parameters and set those variables and play to try and get some understanding of what various levels of hearing loss, various types of hearing loss. They do have examples of CAPD on these disks, as well-- what they might be like for learners. And for those of us who work in the field of deaf-blindness, this Sensory Perspectives set of CDs is absolutely fantastic, because in addition to allowing us to play with and experience simulations of hearing loss, they also have the same set of simulations for vision loss. The CDs allow you to combine that and set visual loss 20 over 70, plus a moderate hearing loss. How would the world sound and look to a learner with those concurrent losses? So it does provide us with a lot of opportunity to try and get inside the student's world and figure out what auditory and visual information might look like and sound like to them. So on that note, thanks for your attention today, and I hope you find the information helpful.