Cochlear implant mapping

4 05 2010

I’ve had 5 “mapping” sessions since activation. A mapping is a reprogramming of the cochlear implant, to readjust the electrical stimulation limits of the electrodes as each user’s brain adapts to sound and fibrous tissue grows over the internal implant. Mappings are typically carried out once a week for the first 6 weeks, then every few months, then twice annually.

At each mapping I was given increased volume and it was an opportunity to address any concerns with the audiologist. This was followed by a coffee break in the hospital cafe then a speech therapy session. I have one more mapping session this week, then my next one is in June when I have my 3 month check.

It’s been a rollercoaster ride. I’ve started with beeps and pushed so hard that I got a constant whine when I put the implant on. This set me back and I had to slowly build up my tolerance again of high frequency sounds from zero, bit by bit, and have successfully avoided a reocurrence of the whine. I have not yet reached full volume, there is still some way to go, which is kind of scary. I found last week quite difficult as everything seemed too loud and I started feeling stressed, but I hung in there and carried on wearing the cochlear implant until I got used to the increased sound levels.

Increased sound levels can be problematic for cochlear implant users because they are more sensitive to loudness changes. A normal hearing person can hear a wide range of sounds from very soft whispers to loud rock bands; this dynamic range of hearing is about 120dB (normal speech is within the 40-60dB range). However, a cochlear implant processor’s input dynamic range (IDR) or sound window is limited to an electrical current of 20dB, and 120dB of sound needs to be compressed into this. Therefore the cochlear implant user is more sensitive to changes in loudness than a hearing person.

If the IDR is small, sounds outside the IDR need to be omitted or compressed; sounds that are too quiet will be cut off, and sounds that are too loud will be compressed and will sound distorted. The 3 main brands of cochlear implants have different IDRs; Advanced Bionics has 80dB, MedEl 55dB, and Cochlear 45dB but with autoranging. I currently have my IDR set at 60dB.

What actually happens in a mapping session? I replace my processor’s battery with a direct connect input lead to the audie’s computer and put the processor back on my head. (Yeah, this freaked ME out the first time I did this).

The audie’s software will reprogramme my implant’s Harmony external processor.

My cochlear implant has 16 electrodes and when each one is stimulated, I will sense each stimulation as a beep.
The audie will set the Threshold (T) levels [to access soft speech and environmental sounds] and Comfort (M) levels [the amount of electrical current required to perceive a loud signal] for each electrode by judging the most comfortable and the highest stimulation I can tolerate – the most comfortable and loudest beeps I am happy to listen to.

I use the loudness scaling chart to indicate to the audiologist which level each stimulation correlates to, ranging from ‘Just Audible’ to ‘Too Loud’.

Then the audie ensures the M levels are similar in terms of my perception, so that the volume is the same in each electrode – I was able to tolerate very high levels of high frequency sounds this week but she brought these back down, otherwise everything would have sounded weird and unbalanced.

This mapping method is rather tedious and drawn out over several months. Clarujust is new software (currently in FDA trial) from Audigence Inc where the patient and processor are interfaced to a computer and words are played and repeated as heard, the software adjusting the map accordingly. Mapping this way reportedly takes 30 minutes. This software can be used by all hearing aid and cochlear implant companies except Advanced Bionics, however Phonak signed up with Audigence Inc this year prior to the Advanced Bionics/Sonova acquisition.

When a mapping is new, it tends to sound louder, until I get used to it. It takes 3 days to get used to a new mapping, then I find loud sounds have become softer and more tolerable, and I can hear a wider range of soft sounds. It is uncomfortable turning up the volume of life to the max every few days. I still have to brace myself for the jolt first thing in the morning, making the transition from complete silence to a full technicolour river of loud sounds pouring into my brain. Amanda’s Tip of the Day: If you wake with a hangover, take your time to put on your CI and turn down the volume. It helps. A little.

It’s an amazing learning process as I am also trying to identify sounds as well, discovering amazing new ones, and learning to discriminate between things that sound similar to me. My hearing is like a baby, it needs time to learn and grow, but it can be fun too.

Erber’s model set forth 4 levels of auditory skill development;

    Awareness of sound (presence v absence)
    Discrimination (same v different)
    Recognition (associating sound/word with meaning)
    Comprehension (using listening for understanding)

I have now reached the second level, I am hearing things but finding it difficult to discriminate between some sounds. Obviously, this means I am still lipreading. In my speech therapy session this week, I discovered I can’t distinguish between Gear v. Dear, tIme v. tAme. I can listen and fill in a word missing in a written sentence, but listening to a whole sentence and being given one written word is more difficult. With hearing aids, both tasks would have been impossible.

In addition to mapping, my progress is occasionally evaluated with an audiogram and speech perception performance with the cochlear implant in a soundproof booth. These tests assist the mapping process and indicate any further adjustments required. I expect I’ll have this done this week, and hope to have improved upon the 18% I achieved in my last speech perception test.

I was programmed with ClearVoice last week but am still adjusting to my new mapping, so I have just been ‘tasting’ this wonderful addition. I tried it on the train; the roar of the train engine and clashing sounds (brakes or pressure pads? – haven’t worked this sound out yet) dropped away significantly and I could clearly hear voices around me. It was awesome. Yesterday, I was sitting by a window and became conscious of this sound. I realised it was the rain spitting outside. In the garage, I could hear the drumming of the rain on the roof and the traffic outside. With ClearVoice on, the traffic became very quiet and the rain became a very clear high PLINK PLINK PLINK, and a lower PLONK PLONK when it came through a hole in the roof and landed on an object. Again, awesome!

Try out the ClearVoice demo for yourself. Don’t forget to say the mandatory WOW!

Shanti is waiting for her cochlear implant operation date and works as a personal trainer and complementary therapist. She gave me a super aromatherapy massage yesterday and I left feeling very relaxed. As soon as I left, I plugged into my iPod and was amazed to hear that the tinny / Donald Duck tone of vocals had gone from a lot of songs. Perhaps there is a link between relaxation and better hearing. Today, voices sound largely normal and it’s so so so NICE to have some normality again!

Photos courtesy of Byron





Dancing into a new life

29 03 2010

It’s been four days since switch-on and my bionic hearing is changing quickly. On Wednesday, I was able to detect a few sounds but they were all beeps. I started to pick out people beeping around me like little birds, items being banged set upon my desk, pages being turned in a series of beeps, the phone ringing in a beep. I had been given three levels of sound on my processor, which was expected to easily last me until my next visit to the audiologist’s, in five days time. On the second day, the volume of the beeps was getting quieter and quieter, and I kept increasing the sound. I started to detect my work colleagues’ voices, with an accompanying beep. I was able to detect a glass being filled with beepy water and draining down the sink’s plug hole, a kettle boiling in mini beeps and switching off with a ping, a crisp packet being beepily rustled. I was getting rather beeped off!

By Thursday evening, I didn’t have any more volume to add on my processor and I didn’t want to wait until Monday’s audiology appointment and miss out on any progress. So there I was on Friday morning, banging on my audie’s door, and she gave me a big increase in sound levels on the processor. She can’t believe how fast I am progressing and has told me to slow down, that my brain needs time to take it all in or I might hamper my progress. She thinks it is because I have done so well with my hearing aids that my brain is very well developed at listening so is able to make sense of the new cochlear implant sound more quickly. My audie said a lot of people take a month off after switch-on to relax at home and take in the new sounds, then they have a shock getting used to their usual routine when they go back to work. Considering I am facing a month of crappy sound whilst my brain adjusts, I reckon returning to work is the smartest thing to do. Just before I left the audie’s office, I realised she wasn’t beeping when she was talking to me.

*hurrah!*

It was Friday afternoon and I was back in the office. I was shocked to find that I could make out my colleagues voices without beeps over the top, their voices sounded distant, in high tones, but I could make them out. It was happy tears all round and a very emotional day. I was amazed that I was able to hear through a computer in my head.

I received a very kind gift from Patrice, Bob and Kirby – a pretty seashell for my New Ear Day, very appropriately reminiscent of a cochlea – and beautifully polished until it shone. I have spent the three days since activation working as normal and that means listening and taking in sound from clients all day, chatting to my interpreter, colleagues and friends, going to the usual noisy cafes for lunch. I think all this has really helped me to ‘acclimatise’ to listening through a computer. It was wonderful to hear a voice and not a beep, and it really helped with my lipreading – which I found a lot less stressful.

Voices now sound quite weird as my brain adjusts to the new sound, and I am having great difficulty understanding what is being said today. I expect to go backwards sometimes as I adjust but to carry on moving in the right direction. I can see that there are so many different shades of hearing. Moving from silence, to sensations or beeps, to detecting some environmental sounds, detecting voices and life around me, moving on to comprehending sounds and then – finally! – understanding speech. My Holy Grail is to understand speech without lipreading. A bonus gift would be to enjoy music. I’m on Advanced Bionic’s HiRes-S with Fidelity 120 program and will get an additional program in May 2010 called ClearVoice, which is revolutionary in having the ability to reduce background noise or the ‘cocktail party effect’. So now I have my goal in sight.

My sound database is now constantly being populated with a drip-feed of familiar, new and sometimes surprising sounds. Familiar sounds I can now hear are the dog barking next door, cars passing me, and sometimes footsteps. When I walk through a busy place such as the cafe in our office building, I don’t experience the usual wall of indecipherable echoey loud white TV noise that hurts my ears and makes me want to scream very loudly, but instead I detect the quiet chirping of people’s voices. (I know from Amanda, the cutlery will become my new sound from hell). At the moment my window of sound is still quite small, because I would not be able to cope if the audie let me have it all at once. It is a mountain that I have to climb slowly, take a rest now and again, acclimatise myself bit by bit. So at the moment, I am only able to hear high frequency sounds that are not too far away from me. I have tried listening to my iPod and music sounds absolutely rubbish, however the volume is set much lower (my hearing aid required the maximum iPod setting and hearing aid setting). I’ve bought my first audio book, Harry Potter’s first book, and find that very hard to listen to as the sound makes no sense – what I am hearing sounds like a long wail with gaps. But I’m holding the faith! Here’s why ….

New sounds from my cochlear implant are the Blackberry / Mac / remote control keys clicking, cutlery on plates, plastic bags rustling, scissors cutting plastic, clicking fingers, bus doors thumping shut, my dog panting and whining (he sure whines a lot!), using an eraser, the bathroom door lock and light clicking from the room next door, the doves and pigeons making a racket in my chimney, my own breathing and sniffing, zips, Amanda’s jaw cracking every time she opens her mouth – all these tell me that the cochlear implant is already outperforming my hearing aid. And it’s only been FOUR DAYS! I am realising that when something moves, it makes a sound. The first sound I could hear clearly, sounding normal and without any pesky beeping, was my shoes scraping on the tarmac when I walked my dog yesterday morning, and I took great pleasure scraping my shoes (and dancing) all around the park. Unfortunately, I now need a new pair of shoes.

I am amazed that I put up with such crappy hearing for so many years.

Bye bye, Crappy Hearing Aid.

Hello, ‘Borg with new shoes.

New, polished, and shining with pride. ~ Come dance with me!