The Curious Hybrid (EAS) Cochlear Implant Recipient


Greenwood tonotopic chart courtesy of Med-El

Greenwood tonotopic chart, courtesy of Med-El
Click to enlarge

We at The Hearing Blog are strong supporters of cochlear implants (CI’s); but this particular case of a recipient who has progressive hearing loss implanted with a short electrode hybrid at the University of Iowa has piqued our curiosity…

We at The Hearing Blog are strong supporters of cochlear implants (CI’s), as they have clearly been shown to transform the lives of recipients in such a way they are the most successful and effective implantable prosthesis, both in terms of restoring function to recipients and improving their lifestyle; and the one-third of a million people who have received CI’s to date can attest to this.1 What’s more, as both qualification standards are being relaxed and implant circuit & stimulation technology leap forward, one need not wait until hearing aids deliver no benefit: As skilled CI surgeons are getting better in preserving residual hearing, the so-called “hybrid” CI-hearing aid combination for high frequency “ski-slope” hearing loss is gaining ground, with the Med-El DUET2 system having TÜV approval (CE marque), and the FDA advisory panel voting on November 8th to recommend approval for the Cochlear Nucleus L24 device,3, 4, 5 with much of the research being conducted at the University of Iowa. 

January 1 Update: We added source documents from the November 8th FDA panel meeting in the References section at the end at entries 3, 4 & 5.


Electroacoustic stimulation candidacy audiogram

Electroacoustic stimulation candidacy audiogram
Click to enlarge

The hybrid system device uses a short electrode placed in the basal portion of the cochlea where high frequencies are detected, and a hearing aid is also used to amplify lower frequencies with parallel processing of the electrical and acoustic stimulation, or in cases with normal low frequency hearing, just an open ear. Almost four years ago we added Phonak FM Engineer Ben Heldner’s blogs2 on his Med-El DUET2 implant experience to the blogroll section, as it provides a good glimpse into what it entails.

As electroacoustic stimulation technology gains ground, we will be seeing  stories appear on social media, such as this wonderful YouTube video of 14 year old Shelby Rheinschmidt of Burlington, Iowa, implanted with residual hearing preservation by Bruce Gantz MD at the University of Iowa; and we wish her well with her newly restored hearing:


This professionally made video was posted to YouTube on the official University of Iowa account on October 26th, 2013; and then on the University of Iowa Cochlear Implant Facebook page on November 1st.

Where this video gets curious:

Shelby Rheinschmidt's right ear probe microphone (real ear) measurements of her hearing aid. Note the red line is her thresholds in dB SPL (re 20µBar) and not in dB HL, as the DSL5-I/O method uses an "SPL-o-gram."Click to enlarge

Shelby Rheinschmidt’s right ear probe microphone (real ear) measurements of her hearing aid. Note the red line is her thresholds in dB SPL (re 20µBar) and not in dB HL, as the DSL5-I/O method uses an “SPL-o-gram.”
Click to enlarge

As we watched the video, at the 1:05 mark something jumped out at us: Quoting her father, she had a pretty good loss when she was 2 or 3, but recently it spiraled downhill. However, she’s been missing the high pitch noises for most of her life. Then, at 1:45 her mother says, her hearing had dropped off, I mean there was a dramatic change from the last years’ hearing test to this years’ hearing test.

As we understand it from several CI surgeons we have asked, the hybrid CI system is really only for patients who have a stable hearing loss, and not for those who have progressive hearing loss as Shelby has, as it will soon require revision surgery to install a conventional CI.

We welcome an explanation…


  1. Wilson, Blake S; Dorman, Mike F: Cochlear implants: current designs and future possibilities Journal of Rehabil Res Dev 2008;45:695-730
  2. An exciting life with deaf ears: Phonak FM Engineer Ben Heldner’s blog on his experiences with his Med-El DUET2 CI system
  3. Cochlear America’s 112 page PowerPoint presentation UCM375000 for the FDA’s Ear, Nose, and Throat Devices Panel Meeting on November 8th, 2013 (PDF file) [Editor’s Note: On page 44 we added balloon notes for the cities of the investigators.]
  4. FDA 90 page PowerPoint presentation UCM374999 by Vasant Dasika PhD for the FDA’s Ear, Nose, and Throat Devices Panel Meeting on November 8th, 2013 (PDF file)
  5. FDA 66 page Executive Summary UCM373792 prepared for the November 8, 2013 meeting of the ENT Devices panel (PDF file)
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About the author

Dan Schwartz

Electrical Engineer, via Georgia Tech


  1. ward
    April 2, 2014 at 9:27 pm

    i’m in this boat also. I’ve had progressive hearing loss since youth with the “ski jump type” chart and loss in high frequency range. Just talked to a surgeon today about types of implants and she was recommending doing a short insertion to preserve my residual hearing. But i was wondering what happens as my natural hearing keeps getting worse. Has there been a consensus about the best approach?


  2. Jason Wigand
    May 10, 2015 at 11:06 am


    If/once residual hearing is lost after an individual is implanted with the hybrid electrode, reimplantation is not immediately indicated. Alteration of the FAT (frequency allocation table) for the shorter array to cover a greater range of frequencies is first recommended. Which, indeed, can cause additional personal adjustment and rehabilitation to perception of new sound quality.

    • Dan Schwartz
      May 10, 2015 at 2:12 pm

      Jason, many times reimplanting with a conventional electrode is not possible, as fibrous tissue growth in the scala tympani occurs — And in fact is often the cause of the residual hearing loss to begin with, often due to poor surgical technique.

      Frankly, we’re surprised that the FDA approved the Nucleus hybrid, as in Cochlear’s FDA presentation they revealed that as many as 36% of people lose their residual hearing at six months and 44% at three years; however there was also wide variation in loss of residual hearing at the various clinical sites, which points to lack of skill and/or poor technique of the surgeon.

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