Hearing management

19 August 2004

Marissa's audiologist speaks

Hearing is more than just registering sounds - it's about making sense of those sounds. And this is not always easy, as Marissa's journey to hearing has shown.

I have seen Marissa a number of times since she was fitted with her hearing aids, and it became apparent that she has very sensitive ears that became irritated by the earmoulds quite easily.

This was aggravated by the fact that Marissa touched her ears a lot initially, pressing on the earmoulds, which caused small pressure points to form in the one ear. We tried different styles and types of materials and gave Marissa a few days to experiment with each. She always came back with useful information and every time we got the earmoulds closer to a perfect fit. The last time I saw her, we were both happy with the fit and the sound of the earmoulds and hearing aids.

Usually, the fit of the earmoulds are perfect straightaway, but a number of factors made Marissa's case a bit more difficult.

Marissa's case not a simple one
Firstly, her hearing is classified as a profound to total hearing loss, meaning that she has almost no usable hearing left. To amplify sound to a level where Marissa can start hearing a difference, we had to set the hearing aids on maximum. When the output of the hearing aid is that high, there is always a risk of feedback (whistling sound) as amplified sound escapes and is amplified again by the hearing aid (much like when a microphone is held too close to a speaker). Therefore, it is important to have a tight sealing fit to prevent feedback from occurring.

Secondly, Marissa has extremely sensitive ears, which got irritated easily, especially with certain types of materials.

Lastly, recurring ear infections and swollen ear canals stretched the timing of the process a bit, since we had to wait for her ears to clear up every time before we could continue. It was quite a challenge to overcome these issues, but with the help of different experts and a lot of patience, we got the earmoulds right.

And you thought hearing speech was easy
Throughout all the sessions that I have seen Marissa, she has always amazed me with her progress. Once again, when you look at the theory, it dictates that she will most probably have only very limited benefit from hearing aids, as I discussed initially. Her hearing test showed that she has no middle and high frequency hearing left and that most of the low frequency sounds are experienced by her as more of a tactile feeling than a sound. However, it is astonishing to see how much benefit Marissa gets from her hearing aids, regardless of how little sound she can probably hear. To give you an example: speech is a very complicated sound to decode. Speech sounds have many different frequencies and some are louder than other.

Allow me to demonstrate: just in the word [speech], the intensity (volume) and frequency of the speech sounds vary as follows:

  • [s] is a soft, high frequency sound (±12dB, between 4000-8000 Hz),
  • [p] is a middle frequency sound (1000-2000Hz), ± 25 dB
  • [ee] is a louder low frequency sound (± 500 Hz, ± 40dB),
  • [ch] is a middle frequency sound (± 1000-2000 Hz, ±35dB)
(from the Northern & Downs Acoustic-phonetic audiogram)

This just goes to show how hard our brains work to decode one word, let alone a sentence! To top it all off, after it has decoded the sound as illustrated above, the brain still has to decode the meaning of the sounds that it has just heard, in the context that it was heard. Complicated stuff. But something normal hearing people do almost effortlessly, as we have had a lot of time to practice since infancy, and something we all take for granted.

If Marissa's audiogram is taken into consideration, it is debatable whether she would really be able to hear middle and high frequency sounds, let alone soft sounds in those regions. Yet she seems to have made remarkable progress in speech therapy (a report from the speech therapist to follow later).

Unfortunately Marissa has had bad luck with her health over the last month or two - she had a recurring middle ear infection and her ear canals were swollen, which meant that she couldn't wear her hearing aids for a number of days. This is very frustrating to Marissa, as she now has learned to rely a lot on sound, as is evident from her reports (she even reported that her skin used to be very sensitive to touch, but that this has changed since she started wearing her hearing aids!). Now that Marissa has grown used to a world of sound again, she hates being without her hearing aids.

Hearing an emotional issue
It is also interesting to see how Marissa has gone through a number of emotions regarding sound and her hearing. Most people with normal hearing would not be able to understand this, but it is actually quite common for people who have a hearing loss and who have started wearing hearing aids. The biggest emotional roller coaster ride happens during the early stages, as they experience new things, which bring with it the normal dose of emotions such as fear, anxiety and happiness, sometimes even tears. The emotion can be linked to the sounds, or to the own journey back into a hearing world.

The best way to explain the emotion of sound, would be to use the example of someone who has travelled overseas and who hasn't had contact with their loved ones for quite some time. Once they are able to talk to their family on the phone, it will often bring tears to their eyes to be able to hear those familiar voices. Sound can be very emotional. Just think about how the background music in a movie can add to the emotion of a scene. A sad song when they say their goodbyes, an upbeat number when it is a joyous occasion. Do yourself a favour - next time you rent a horror or thriller movie, turn down the sound on the scary parts and you will see how the whole situation seems a lot less scary, sometimes even laughable.

Marissa was disappointed with the sound of a waterfall and the sea. She expected it to sound different, but she was overjoyed to hear the sound of a fly buzzing (something we might think to be annoying!), the sound of rice cooking on the stove, or her slurping soda out of a can. She was scared when she first heard the sound of hard rain on a tin roof and was anxious when she heard her patient making gargling sounds while she was busy doing a facial on her - this turned out to be a very comical moment, as the lady was actually fast asleep and snoring! (If it is that relaxing, I think I must go for one of Marissa's facials). Marissa also mentioned to me that she never knew that so much emotion could be conveyed by a person's voice. She used an example of someone swearing, and said that the persons' voice is usually harsh when they swear (harsh emotion), and that she doesn't like it.

Other's unrealistic expectations can hurt
When it comes to Marissa's journey, her emotion has also had a lot to do with how people reacted towards her - most of us take hearing for granted and do not fully understand the implications on everyday life when you have a hearing loss. Initially, Marissa was overjoyed to hear all the different sounds, and this still happens often. But a lot of the people around her had unrealistic expectations of what her new hearing aids would enable Marissa to do, especially if you take Marissa's history and the profoundness of her hearing loss into account. Even Marissa was frustrated at some point, because she wanted her progress to be faster!

However, since she hasn't worn hearing aids for the biggest part of her life, her brain has to learn a lot of things we take for granted, as I have illustrated with the example of the word [speech]. The timing of this learning process depends heavily on the severity of the loss and on how long the hearing nerve and brain have been "depraved" of sound. For people with a slight or moderate hearing loss, this process can be very quick, taking anything from a week to six weeks.

In such cases, it is more of a relearning process than a learning process. I call this relearning the "labelling phase".

How the labelling phase works
Usually a hearing loss develops gradually over a number of years, and the brain is not even aware of how many sounds it doesn't hear anymore. Once you put hearing aids on, the brain seems to be overwhelmed with sounds it never even knew it missed out on, so it has to give attention to each and every sound to figure out what it is. Let's say, for example, the person hears a funny sound, turns around and sees that someone has opened a tap and the sound they heard was tap water running into a basin. The brain labels the sound as tap water running into a basin. The next time the sound occurs, it will sound familiar already, but sometimes, the person will still have to turn to double check what the sound was. Once they see the source of the sound, the brain will go: "Oh, yes, tap water running into a basin". Possibly, by the third time, the person wouldn't even have to turn around to identify the sound, as the brain has labelled the sound already and has pulled it out of the archives for everyday use.

This labelling or relearning phase can be very tiring, but once you have gone through it, hearing and listening becomes much more automatic. When people report back after their first week of hearing aid use, they normally say something about the refrigerator buzzing when it starts a new cycle, or a clock making ticking sounds. If you ask them about those sounds three weeks down the line, they don't "hear" it any more, as the brain has labelled it and accepted it as part of the home sounds.

For Marissa, the process of hearing and understanding speech in particular, will take much longer than six weeks, mainly because she isn't really relearning sound, but learning it for the first time. It is also a lot more difficult for her, since she cannot hear all the frequencies, even with hearing aids. I think that Marissa is much more at peace, realising her limitations, but still very focused and positive towards the future. It is precisely this attitude that motivates her and allows her to do more than we thought possible. (Carina Visser, audiologist)


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Hearing Expert

Francis Slabber is a Speech & Language Therapist and Audiologist who has owned and run The Hearing Clinic in Wynberg, Cape Town for the last 17 years. Francis and her team have extensive experience in fitting and supplying hearing aids as well as assistive living devices. Francis has served as the Western Cape Chairperson for the South African Association of Audiologists for three years and has given many talks on the topic of hearing loss and amplification. The Hearing Clinic has a special interest in adult and geriatric hearing impairment, hearing aid fittings and hearing rehabilitation.

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