I am certain – that is the big question that interests most of the readers of my blog. That is also the reason why it took so long for me to write about my first hearing impressions. Until today I do not really know how to describe the sensations.
Foremost it is unbelievable that suddenly, after being quasi deaf (95% hearing loss) on my right ear since October 2020, I hear something again – this is simply mind-boggling!!!
Above is my current audiogram. On my left-hand side, I am close to normal hearing, but I do wear a hearing aid to compensate for the 4kHz dip.
I can hardly imagine how a switch-on effects somebody with a bilateral deafness or even a person who was born deaf. This must be an overwhelming and I am sure a very emotional experience as well.
I try to understand it mainly trusting my knowledge in audiology, psycho acoustics and hearing instrument acoustics but so far, I am only partially successful😉
What happens during a switch-on?
After choosing the right length for the T-Mic and checking the placement of the speech-processor as well as the correct strength of magnet used to hold the external part of the coil in the right place, Nicola de Min gave me a short instruction on how to handle the AB Naìda Q90. The speech-processor was connected to the adaptor and I put behind my ear for the first time. Awkwardly I tried to place the magnet where it is implanted contra-part was located.
And there it was – my first real surprise.
The HiRes Ultra 3D-implant has 4 magnets that can be moved in any magnetic direction. Through that it is possible to go through MRI procedures up to 3 Tesla.
Now, the surprise was that the movement of the rolling magnets positioning themselves to the magnetic field is very audible. Today I experience this sound as an audible confirmation that my magnet is positioned and holding well.
But… so far, no other hearing impressions over the sound processor. Nicola de Min started to make me identify the hearing threshold in all 16 channels of the electrode array.
At the beginning I had no clue what to listen for. After a while I realized a kind of a buzzing noise emerging from continuous broad band noise of my tinnitus. Depending on the frequency it was more of a chirping, buzzing or humming sound. But it was definitely something else than my tinnitus.
The second task was form me to identify the level of comfortable loudness. This was easy compared with the task before and it was simply fun to be able to hear sounds above the hearing threshold. The sounds I heard were no tones I knew but it was some sound created by a synthesizer to me.
My first map revealed that all electrodes except electrode nr. 14 were working. Until today I had no hearing impression with electrode nr. 14. We decided to still activate this electrode as all the others just in case there was a change to this electrode.
This will be rather important later during my adaptation to the CI.
Changing the input source to “live-speech” I had to close my good left ear to hear how the cochlear implant sounds. It was somehow without body. It was buzzing, chirping, and humming and speech sounded somewhat speech-like but quit far off, especially compared how it sounds to my nearly normal hearing left ear.
On the table above my first map is shown. All 16 channels are active as well as the channel 14. We adjusted it in the same way as the neighboring channels just in case I would start having some hearing in that region. And secondly to try stimulating the neurons in that region of the cochlea.
The extremely high impedance of electrode 14 ad a hampering effect on all other electrodes as we learned later on.
That is the report to the map as I am using it now in my speech processor. The deactivation of electrode 14 has altered the pulse width as well as the channel rate roughly by the factor 10. By fixing the pulse width manually to 20.7µs we could even gain a somewhat better experience for me. With my first map we had a pulse width of 229µs (APW II) and the channel rate was improved from 291pps to 3228pps.
For me this made a really big difference. One of the most important changes is that I can hear the sound with more “body” now. One could say the robot voice has become more human. Now I hear some sounds first with my CI even though I have still a hard time telling what sounds those are. But asking my wife and realizing what the sound was it normally makes sense.
The psycho-acoustic aspects and the importance of the adaptation as well as the hearing-training methods most helpful to me will be discussed in my next blog entry.
Only a little teaser up front:
As one can see from my audiogram, I do have a 4 kHz dip on my good left ear as well. Since I wear a hearing aid as compensation of this 4 kHz dip my special hearing has improved dramatically. Secondly, I do have a nearly symmetrical hearing experience wearing the CI and the hearing aid. The very high-pitched sound of the CI is much more comfortable for me while wearing the hearing aid.
Thank you very much for your interest
Your hearing car specialist, cyborg and CI-Punk - René
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