Parsing the CI Rabbit hole

[FarmTownBob]

Hi folks - new here.  I broke my 8 year old hearing aid in October 2017 and my audiologist confirmed my hearing had advanced to the Cochlear Implant stage in my left ear.  I went to Washington University School of Medicine in St. Louis, a three hour one way drive from where I live in Illinois,  to begin my journey and see if I was eligible for a CI and to see where my right ear resided.  My first appointment was mid december.  They verified my left ear was totally ineffective and my right ear, aided, had 73% word recognition.  I also began my research into the three companies and what they have to offer as well as learn more about what CI is in general, how it works, what is done, etc. etc.  I have learned a LOT by this time.  I also signed up for all three company help groups and some social media forums to get people's experiences and points of view.

I went back to St. Louis on January 25 for a CT scan and to do more testing with my audiologist.  This time, we further proved the left ear was totally ineffective, and the right ear had fallen 10% in aided word recognition scores.  I also got to see in person each of the manufacturers options and equipment.

I've been looking mostly at the MedEl flex internal array, as that seems to be the most advanced on the market.  However, since I have to go implant and hearing aid, I have the Advanced Bionics option as well.  I am at a quandry to learn more about the technical fine details of Med El's electrode array and how it is different from AB.

[Mary Beth]

Wishing you the best @FarmTownBob!

 

I do not know anything more about the differences of the electrode arrays between AB and Med-El than what you can find with an online search.

 

I have friends with AB and they do well with their CI.  However, some are not able to get the newest AB processors because they do not work with their older internal implants.

 

Before choosing a brand, I never even considered backwards compatibility.  Thankfully Med-El does make new processors backward compatible.  Just something to consider.

 

wishing you the best

[MED-EL Moderator]

Hi @FarmTownBob, 
 

Welcome to HearPeers! It's great to read that you are being so thorough with your research -- it's a big decision and worth spending the time and effort making the right choice for your hearing. If you're interested in reading more about MED-EL's electrode arrays, you might find this blog post interesting: https://blog.medel.com/why-does-med-el-have-so-many-electrode-arrays/. 
 

And if you have any more questions at all, we're always happy to help! 

 

Kind regards, 

Mary 

 

 

[FarmTownBob]

Thank you so much for the technical directive.  I have other questions which now I will turn to other parts of the forum for answers.

Thanks so much for the help.  Have a wonderful day.

[hadron]

Hi @FarmTownBob

Glad to see you doing your homework. AB does not have a large variety of electrode arrays like MED-EL. Currently AB has 2 main electrode arrays. The Mid Scala and the SlimJ.

 

 

[FarmTownBob]

What about AB's Hires 1J and Helix?  Also, AB has the ability to activate dual electrodes simultaneously which allows theirs to have virtual electrodes which stimulate the hairs adjacent to each electrode as well, so effectively 16 electrodes become a virtual 120.  To me, that allows more overlapping stimulation and the possibility to blend frequencies better.  I'd almost go so far as comparing it to the difference between the digitality of CD recordings and Vinyl recordings.  There are nuances in sound you lose, whether at a noticeable level or not, when you go from a blended sound to one that is digitized into 1's and zero's.  Yes, I remember the big fight in the audio world between purists when CD's took over as the mainstream media for music.  I do not see MedEl' advertising as having this ability in any of its electrode arrays.  Correct me if I am wrong please.

This is where the electronics of the "graphic equalizer" [as I call it] or the chip in the implant itself that manages electrode control is important to me.  I haven't found detailed information between the big three on what that chip is, what it does, and the differences between each manufacturer's technologies.

In analogous geek terms, who's running an AMD processor with a X360 chipset and soundaudigy processing, or  an Intel processor with a Skylake chipset and Realtek audio processing, or is it an Apple technology system [personally I willfully avoid Apple products]?

cochlearimplantcomparisonchart_v6-1f.pdf

[Mary Beth]

I believe Med-El delivers up to 250 pitches if all 16 electrodes are turned on.

 

[Mary Beth]

Link to 250 pitches

 

http://www.medel.com/au/finehearing/

[Mary Beth]

Parallel stimulation of selected electrodes is part of the FS4p speech processing strategy.

[Mary Beth]

Link to parallel stimulation and Synchrony’s ability to extend that further 

 

https://www.audiologyonline.com/ask-the-experts/what-benefits-med-el-synchrony-15156

[dare_v]

Excuse my ignorance Mary Beth, but isnt CI532 smaller than SYNCHRONY?

[Mary Beth]

I’m sorry.  I do not understand your question.

[hadron]

Hi @FarmTownBob, the SlimJ is the following-on to the 1J. I don't think you will see it used much anymore. Helix is their perimodiolar electrode array though mid scala is also one.

The mid scala is referred to as the Swiss Army knife of electrode arrays, it can be used for almost any surgery but it is usually not the first choice when deciding on an electrode array.

 

 

[hadron]

Hi @FarmTownBob the ability to stimulate adjacent electrodes simultaneously to create virtual electrodes is called current steering and was actual developed by Blake Wilson/MED-EL. They found it did not significantly improve performance because of current spreading and moved on to create a more detailed sound code strategy called Fine Structure Processing.

AB adopted the current steering approach and created a sound coding strategy called HiRes F120. Unfortunately due to current spreading the F120 approach has channel interaction issues which reduces it's effectiveness. AB has used current focusing and creative stimulation modes to improve effectiveness. F120 use a FFT with a fixed number of frequency bins to separate the information for each frequency range.

MED-EL Fine Structure Processing (FSP) is a more complex sound coding strategy which includes creating virtual electrodes.

In contrast to AB F120, Fine Structure Processing uses time-domain filters for filtering (AB uses an FFT with a fixed number of frequency bins). Time-domain filters are more natural and allow you to even replicate the delay mechanics of the basilar membrane in the inner ear to some degree. A change in sound frequency can only be perceived if that change leads to a change in the stimulation levels that are output by the implant. So, FSP calculates the minimum change in sound frequency that is required at the sound processor input to produce the minimum possible change in stimulation level created by the implant on at least one electrode. If you do this calculation across the entire input frequency range (100 Hz to 8500 Hz) then you can sum up the number of minimum changes in frequency in that entire input frequency range. The result for this number for a standard MED-EL CI fitting map is slightly over 250 as @Mary Beth stated.

Those 250 values are available to a CI user that uses the standard MED-EL fitting parameters. If, for example, channels are switched off, then that number changes, similar to like the number of frequency bins changes in the AB system. However, this number defines the upper limit for how many pitches a CI user can hear through the system in principle. The actual number of pitches a particular CI user can then perceive still also depends on a lot of subjective parameters like, e.g., neural survival, and this is the reason why the number of virtual pitches varies greatly between users, even for the same CI system.

[dare_v]

12 hours ago, Mary Beth said:

I’m sorry.  I do not understand your question.

You linked a website saying: SYNCHRONY is also the smallest and lightest implant available today. This can be particularly important when implanting babies and young children.

Thats why i asked if it isnt the CI532 which is even smaller and lighter. The electrode, not the implant.

[hadron]

Hi @dare_v. You are comparing an internal implant (SYNCHRONY) with an electrode array (CI532).

You probably want to compare SYNCHRONY with the Cochlear Nucleus Profile internal implant.

[Mary Beth]

@hadron

I love your detailed post a few posts up.  You always have great info to share.

 

I wish I understood the engineering component of our CIs as well as you do.

 

 Thanks for sharing,

[FarmTownBob]

@hadron Thank you so much for the detailed review.  This opens a whole new, and welcome, facet to my research.  I am a technical guy by nature, never had the focus to be an engineer though.  I believe performance can be measured without opinion and bias through the numbers.  That is why I want to know what that little box is actually doing in my head with the processor signal.  Like you mentioned, if AB is using an old MedEl technology they abandoned because of real issues, then It would be in my best interest to look further.  One issue I have with almost anything I buy is getting through the marketing trolls, and people with bias agendas towards their own product.  I had initially chosen MedEl, but the waver for me is the fact MedEl doesn't play nice with any hearing aid.  I sadly cannot persuade my surgeon to go bilateral at the front door, so I have to wait until my "good ear" gets bad enough.  That poses the perplexing position of what implant to go with now.  Do I go with MedEl now, bear the expense of an out of pocket aid which will not coincide with MedEl technology, or go with AB, who has an Aid which will coincide and communicate with the implant already.  Thanks again for the detail.

[Mary Beth]

@FarmTownBob

 

This is from Med-El but does present some interesting things to consider about bimodal hearing.  In case you have not seen it yet.

 

https://blog.medel.pro/bimodal-hearing-cochlear-implant/

 

 

 

[Cara Mia]

Great article, Mary Beth. Thank you for sharing. I didn't see it before. Despite I switch from bi-modal to bilateral a year ago, I am still interested to read such info. I was pretty comfortable to use both my Synchrony CI and Re-Sound HA until I got that just one CI can do work for both just fine in 3 months after implantation.

[FarmTownBob]

Agreed @Cara Mia.  @Mary Beth, thank you for pointing this out.  MedEl had the best first impression on me concerning the technical aspects they offered.  IMHO AB had more bells and whistles to offer.  I'm the kind of person who would buy a used car first and look under the hood and get more facts about stuff like engine, transmission and drive line before I would look at stereo systems, power windows, heated seats and the like.  I feel MedEl is more aligned with this way of thinking, and I see that more and more since I've been on here.  Next issue is expense for the hearing aid.  I've had both phonak and Oticons before so I am familiar with both families, I already wear a lanyard and tie into my phone and all.  I am familiar with the technologies pretty well already.  I know eventually I will go bilateral, so the weight for me is with what will go in my head over what bells and whistles come with the implants.

One question though, after reading the article, what keeps the MedEl implant from becoming out of phase with the hearing aid if they do not communicate between each other.  If the implant and the aid become out of phase, it would generate an echo effect or a time difference between the perceived signals.

[Mary Beth]

I reckon you can ask yourself the same question about bilateral CIs because they do not communicate with each other so are not cycling at exactly the same moment. However, there is no echo.

 

While participating in research and listening with coils attached to Med-El computers, perfectly in sync “processors” can be experienced.  

 

 

[FarmTownBob]

All of the Hearing Aids I have had communicate with each other.  I've had phonak and oticon.  I've always heard better in stereo versus mono.  I imagine the cross communication has to do more with localization than general hearing.  Or is there another reason for the cross communication.

[Mary Beth]

I don’t know the answer to that.  Being able to locate a sound source requires

 

interaural timing differences (sound arrives at ear nearer the source first)

and

interaural loudness differences (sound is louder in ear nearer the source)

 

Research with CI users shows many rely more on loudness differences but some use both loudness differences and timing differences.

 

It’s interesting stuff.

[Kara of Canada]

I currently wear a HA and a Medel implant. Sonnet to be exact. I don’t have any echo effects even though my HA is practically useless. I only have 16% hearng left I’m my unimplanted ear which is nothing by itself. Also you may need to know that when You get implanted you have to retrain your brain to understand the new “hearng” you are receiving. It takes approximately 6-9 months to see actual lasting benefits. I would never go back to a stupid HA. They are far inferior to our CI-borg counter parts. The sound quality is phenomenal. I was unable to hear music or talk on the phone befor implantation and I can easily say I can do these things with ease! Best of luck on your journey @FarmTownBob  it’s a wild ride,,?