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Cerebral Auditory Impairment

Cerebral Auditory Impairment

We know from the people we talk to that where there is a cerebral visual impairment (CVI), for many, there can also be challenges with sound and noise, but these challenges are varied and can seem inconsistent.

As we refer to these visual difficulties as part of the picture of cerebral visual impairment, we use the term cerebral auditory impairment as the umbrella term to encompass these auditory phenomena and potentially other auditory manifestations that may be identified in the future.

One mother wrote:

My son's reaction to sound and noise are completely inconsistent, and noise is a huge problem for us and a great cause of stress for my son. I tried to explain it to audiologists, but they didn't understand that it wasn't a sensitivity, or anything to do with volume or decibels, or certain types of sounds. It is completely inconsistent, he would go from not hearing something, like he was completely deaf, to having hearing so sensitive that he would go into a full CVI meltdown. He would seem to switch from deaf to hypersensitive within seconds, and the noises that were challenging were inconsistent too.

Below, we are going to consider some of the challenges CVI presents about how we perceive and interpret sound through looking at a number of case studies.

Sound Library

Just like we have a library of images in our minds, as we explained in our Recognition sections, we also have a library of sounds. We learn to recognise sounds in the same way that we learn to recognise images. We experience the sound, remember the sound and then are able to recognise the sound when we hear it again, and with every repeated cycle, that memory becomes stronger and stronger. However, what we are interpreting as cerebral auditory impairment can create many challenges to this process, including:

Sound & Simultanagnosia

This mother's account of searching for a woodpecker illustrates the challenges understanding sounds with simultanagnosia can present:

Today I was walking in the woods and I heard a woodpecker and I tried to locate the bird. As I tried to search the dense woods I realised how difficult this was. Might this be what simultanagnosia is like when visually searching in a cluttered environment? Part of me wanted to give up, thinking I'd never find the woodpecker, but mindful of my son's challenges, and encouraged by the drumming of the woodpecker, I continued to search. As I was standing I realised all the other sounds that were present, that I had completely filtered out. The background hum of traffic from a nearby busy road, aeroplanes passing overhead, many different birds, all singing away, and a woman calling her dogs.

How hadn't I heard these noises before? I only heard the woodpecker. Is it because all these other noises were known to me, and my brain processed that as I walked through the woods, and awarded no attention, however, the woodpecker was more interesting so I attended to it? What happens if none of these noises are known because they have never been learnt - what might that be like? When out and about, even in the woods there are many noises - if unknown how might it be experienced if none of the sounds are filtered out? Is that why my son's idea of hell on earth is a busy coffee shop?

Without a filtration system founded on recognition and knowledge, sounds must become unbearable??

Is this why my son loves open countryside, the more remote the better, away from roads, flight paths, voices of people he doesn't know?

Somewhere in these trees is a woodpecker.

This short account highlights a number of challenges:

  • Reduced visual attention due to simultanagnostic vision can entail difficulties creating a visual match to go with a sound, which can make it harder to learn what the sound is coming from.
  • A person may hear a sound (it is perceivable) but because they have not learnt what it is, because they have not been able to match it, it is without meaning, thus they are not able to recognise it in the future.
  • Our brains are brilliantly clever at what they award attention to. Whatever you are doing, stop, and listen, what can you hear? Maybe a clock ticking, or a tap dripping, the hum of a heating system or kitchen equipment, a bird outside or a lawnmower, maybe a car passing. Until you stopped to think about it, how many of those sounds were you aware of? It might follow that an unknown sound, or a sound you associate with needing attention (like the phone ringing or the doorbell) are not filtered out in the same way.

Sound & Functional Vision

For all the reasons above, if vision is reduced for other reasons, due to both CVI and ocular visual impairments, then learning what a sound is, can be more important, yet more challenging. Where there is a communication challenge, for the sound to be explained so as to be learned from, is considerably harder.

To learn what a sound is, for useful recognition purposes, the following need to be present

  • The sound must be heard, that is perceived (see the Sound Computer below)
  • The sound must be meaningful, otherwise it's just meaningless noise.

Meaningful Sound

So how can sound be made meaningful, so it can be learnt?

  • For many with CVI, sound needs to be slowed down to be meaningful, see Gordon Dutton's blog 11 for a fuller explanation.
  • If there are many sounds at the same time, in a noisy environment, it will be harder to separate the individual sounds to learn what they are

The Sound Map

We know that people with optic ataxia have difficulty mapping where objects are. With some, it seems as though there is a difficulty mapping where sounds are coming from too, including how far away (or close) they are.

We take for granted our ability to do this. An aeroplane is heard, and is known to be loud but far away so not a threat, thus we don't try to protect ourselves from imminent impact. However, if you remove knowledge of the sound, from the sound library, this is much harder, as one of our parents discovered...

A few days ago, I was up early when I heard a beep, repeated about every ten seconds. Distracted by the noise I went to find it, and after checking obvious causes (smoke detectors, mobile phones and the cooker timer) I still hadn't found the cause. It occurred to me how difficult it was to anchor a sound when there isn't an obvious visual connection to give it meaning. I spent fifteen minutes trying to locate the beep. Eventually I found the cause - I had accidentally put my dishwasher on a setting I had never used before and it was alerting me that I now needed to press another button.

This really got me thinking about sound, and if sounds can't easily be anchored, how can they be known?

Thus, our capacity to locate sounds effectively relies heavily upon our knowledge of what sounds are from our sound library. Equally however, to know what a sound is, and understand it, to a degree requires the ability to correctly locate it. The sound map and the sound library are intricately interconnected and work in tandem.

Mary, an adult with CVI explains:

I have difficulty visually locating where auditory information is coming from. This has always caused problems for me since my brain injury, although I didn't know what the problem was for a long time. It always happens when someone is calling out to me in a crowded situation, or when I am getting picked up from somewhere and the person calls out to me. I always find it distressing when I can't find whoever is calling me, which has led to me to try to avoid situations where this might happen. My worst nightmare scenario is when someone toots their car horn at me. I have a big startle reflex to noises like a car horn and I get really upset and embarrassed. I think this is another example of CVI related issues causing me to develop certain behaviours to try and cope with the issues.

Many parents of children with CVI at main stream school report that there is no point in calling their children, as they look round unable to find them and unable to locate where the sound is coming from.

A number of families have found that calling their child on the phone from a distance, and telling their child where to look, while they call and wave, has helped their child get better at working out where people are calling from.

Sound Computer

Please take the time to read Nicola McDowell's blog 9, which explains in context what happens when a person has CVI, and how the computer (brain) in certain situations is unable to process more than one thing at a time.

Connor's mother thinks this explains why sometimes he hears things, and sometimes he doesn't...

I don't think Connor can locate where sounds are coming from, or how far away they are - so something that may be loud but far away (e.g. an aeroplane, we live on a flight path) he can sometimes react like he is in danger, and 'hit the floor' or grab someone to be held (protected), or scream / cry. But then sometimes it's as though the aeroplane doesn't exist - we can walk along our little road and three aeroplanes will be ignored, then a fourth creates a severe reaction - why? I think it is to do with what his brain was doing with the first three - busy exploring, processing, there was not enough reserve and they simply weren't heard - by plane number 4 his attention had moved on and there wasn't much interesting going on, and it came out of nowhere at full volume. So sometimes it is as though he can't hear, and other times it is an overwhelming sensitivity, which can be to the same sound only seconds apart.

With this example, we see what happens when the sound library, map and computer are together causing challenges:

  • Connor does not know what the noise is
  • Connor cannot locate the noise
  • Connor cannot hear the noise when focusing on other things, but can when he has less to attend to
  • Connor will not be aware that sometimes he does and sometimes he does not hear the noise (as Nicola McDowell also explained in her blog 9)
  • This makes the noise inconsistent and even harder to learn
  • Connor does not know what the noise is (we are back to the top of this list, and the cycle of not learning is repeated).

When a noise is known, is can be a delight, even if a little scary, as Lucy's mother explained:

Lucy loves playing hide and seek with her gran, who will semi hide and then make low grunts to give Lucy audible clues to her location. When Lucy approaches, gran emits a very quiet gentle roar. I've got you

Lucy always jumps in delighted and says what a fright you gave me. She loves this and it's a well established game they play.

The game has a known safe thrill for Lucy at the end. And Lucy, like many other children with CVI loves music, and actually at home often chooses to listen to two things simultaneously, again, these are all within Lucy's known and meaningful parameters:

She [Lucy] quite likes layers of noise. It's like she switches in and out of various auditory stimuli.Conversations, noisy books, toys that make sounds.She really loves her voice recorder. She's always replaying old conversations or recording us, and playing back scenes from school and home.She would want to have the radio on and listen to her voice recorder at the same time. If she's listening to two things and I turn one off - say the music on the radio - she will immediately request it goes back on.

Looking and Listening

Mary explains:

I am not able to process auditory information when I am overwhelmed by other sensory information, including visual, noise and smells. For instance, if someone is trying to have a conversation with me when there is music going on in the background, I have trouble concentrating on the conversation. I also find that I can't listen and look at the same time. I either have to block out what people are saying to look at the scene around me, or stop processing the visual information to hear what they are saying. And this is not something that I can choose very easily, it just tends to happen and it takes a lot of concentration to try and change it - for instance if I really want to listen to someone instead of looking around, I have to work very hard to shut my visual system off, so that I am not looking around.

Many have shared the same story about not being able to look and listen at the same time. One child has adapted and if people talk slowly enough, she turns her back on them to listen to them. Some may think she is being rude or ignoring them, but she simply can't concentrate on listening to what they are saying whilst simultaneously looking at them.

Sound & Behaviours

We have touched on behaviours in some of our examples. If a sound is not known, when heard it may be:

  • Frightening
  • Not locatable
  • Heard as much louder than other people hear it
  • Confusing
  • Boring

We know many children put their hands across their ears to block out sound.

Heather's mother explains:

My first experience of Heather reacting really adversely to sound was as an 18 month old sitting in her pushchair in France:

The motor scooter is a common mode of travel in France and what was intended to be a pleasant leisurely stroll in the sunshine around a town square resulted in a sharp exit back to the car. Several scooters passed by, accelerating and tooting their horns and Heather's hands went straight to her ears and she became very distressed and vocal.

To this day 15 years on she will react in the same way if we inadvertently end up being passed by a motorbike or such like.

The school have worked hard to encourage Heather to participate in their weekly assembly, which often has a musical content which Heather very much enjoys. Heather would initially refuse to participate as she found the experience overwhelming and would go back to the classroom. However over the last 5 years she has slowly moved her chair down the corridor, towards the assembly, listening from a safe distance. Heather eventually progressed to joining the assembly starting off at its edges, lying on the floor and over time has been integrated into joining in on her own terms, sitting amongst her peers, however, more often than not with her hands over her ears when she feels the need to put them there.

At her daycare centre, over the last 10 years , I have asked them to place her away from noisy peers, or when the service has lots of users and has been busy, I have requested that she be taken out of the centre for the day to enjoy something outdoors. I have done so without really knowing why, just simply that as her mother, observation has taught me that she doesn't like the aforementioned settings and above all finds them distressing.

Now that I think about it, it is a rarity that a day passes when I don't see Heather without her hands on her ears.

So, very slowly, and without being forced, Heather was allowed to take control over whether she went into the school assembly. It sounds as though it is still challenging for Heather, but she clearly enjoys it and has pushed herself to be able to participate. This is a baby steps approach we promote throughout this website.

Heather's behaviour is reactive, and she puts her hands over her ears when the noise is too much for her to cope with.

Connor's behaviours have evolved and are both reactive and adaptive, as his mother explains:

Connor has always put his hands across and in his ears, I took this photo (below) this morning to show something else though. This is not a reaction to an uncomfortable / frightening sound, this is a behaviour. Every school day, Connor is in his wheelchair ready for the bus. When the bus arrives, I sing 'tv's finished'. Everyday, probably as a sign that he wants to stay and watch tv longer, he puts his hands in his ears (his thumbs are stuck in his ears here). Hands in / across ears started as a reaction to sound / noise, but has developed into an additional behaviour - I am not sure if he is trying to communicate that he doesn't want to do something, or thinks that if he can't hear it, it won't happen. Connor is still extremely sensitive to sounds, and the hands go across the ears when he is anxious or frightened, for example if a vehicle with a siren passes us in the car, but he also does it when he knows exactly what is going to happen and it's something he doesn't want.

Connor’s behaviours in relation to noise are both reactive and (as here) adaptive).

So, it's complicated, but we also know all of the people featured also can find sound extremely calming and relaxing, particularly known music and singing.

In summary, CVI can affect the sound library, sound map and sound computer, which are all required to understand and process sound.

CVI can affect the sound library, sound map and sound computer, which are all required to understand and process sound.

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At CVI Scotland we are devoted to helping people understand cerebral visual impairments, and together working towards developing the understanding of this complex condition.