Book Review: Programming Cochlear Implants, by Jace Wolfe PhD and Erin Schafer PhD

January 2015 Update: We have received the second edition of this excellent book, and it is over twice the size of the first edition. We will have an extensive review of it in the upcoming weeks; however a cursory skimming shows it’s even better than the first edition — We recommend it.

Programming Cochlear Implants is a pretty darned good book for a college educated CI candidate,  CI “power user,” or even the parents of a “CI kiddie,” as it provides a nicely detailed view of CI’s, rather than what you can extract from the “FDA-sanitized” marketing hype from the CI manufacturers. This book has some very nice troubleshooting tips, especially for parents and school audiologists. Also, Chapter 7 on hearing assistance technology (HAT), which is mostly all on FM, is very good, as it lays out how configuring FM assistive devices with CI’s differs from hearing aids: In the opinion of The Hearing Blog, this chapter is worth the price of the book alone. One minor shortcoming, though, is that it does lack the channel interference table — The “recommended channels” — for Phonak MicroLink receivers operated on the 168mHz H-band  and 216mHz N-band when they are connected to the commonly used Cochlear Freedom processor, and almost certainly the Nucleus 5 processor.¹

Update: In a call to Professor Schafer, she agreed with this point; and the table will be included in the second edition, when published.

Where this book is quite helpful to the CI user community is pointing out where Best Practices can be (and often are) skimped  to speed things along in busy clinics; and when these shortcuts are taken, should serve as Warning Flags to the astute user or parent. A large part of these shortcuts are due to poor 3rd party reimbursement; but also it’s a bit troubling that the ramifications of the CI audiologist taking these shortcuts in terms of patient performance is not fully discussed in this book, i.e. it’s OK if the CI audiologist has an attitude of “it’s good enough for government work,” which, as an Engineer, this reviewer finds a bit lacking. Most notably, the common shortcut of assuming T levels of 10% of M levels on the AB and Med-El systems will result in an incorrect input dynamic range (IDR) being displayed: It will work, but in an unpredictable manner depending on the actual (measured) T levels the patient has. (Hat tip to Mike Marzalek of CItheory.com for teaching us this important point.)

However, there are two  interrelated shortfalls in this book we hope the authors will address in the second edition: The first is a total lack of useful signal (timing) charts in Chapter 2, instead relying on awkward verbal descriptions of the various stimulation algorithms, as a picture is worth a thousand words. The second shortfall is the almost complete glossing over of current steering and beam forming, which are the processes of simultaneous firing of adjacent electrodes to shift the charge cloud to stimulate intermediate nerve endings for more pitch percepts (Med-El i100 & AB HiRes90k implant circuits);  and firing of alternate polarity charges to adjacent electrodes to get  a tighter, more focused charge pattern, to yield a “cleaner” stim (HiRes 90k only).²

Greenwood tonotopic chart courtesy of Med-El

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

Update: Fully addressed in the second edition.

One item notable by it’s absence is a Greenwood chart graphically explaining the cochlear tonotopic structure vs angular insertion depth of the electrode. Another item notable by its absence is any mention of Advanced Bionics’ ClearVoice noise reduction technology, which received the CE marque in January 2010 and was quickly rolled out across Canada & UK in February & March of that year. Granted, ClearVoice was just approved by the FDA in March 2012;³  but since this book is listed for sale in Britain on the Amazon.co.uk website, at least it was worthy of mention since it’s a released product; and was being beta tested at the AB factory as far back in September 2009.

There was also one minor author-date style annoyance while reading this book: The use of inline references for journal articles and books, as opposed to numbering and placing the footnotes at the bottom of each page. Yes, it’s permitted; and yes, it’s a bit more time consuming when typesetting to do this, but it’s a lot easier on the reader.

Overall, we give Programming Cochlear Implants a 4½ Star rating; and we highly recommend it to CI users, parents of CI kiddies, and to CI candidates.

Bootnotes: 

1) Permitted FM Channels when using the Freedom Speech processor: From page 16 of Phonak’s FM Solutions for Cochlear Implants:

To avoid interference, the following channels are recommended to be used with the MicroLink Freedom
N Band: N09, N12, N13, N16, N17, N18, N52, N57, N61, N62, N64, N65, N68, N73, N76
H Band: H06, H07, H16, H17, H18, H19, H20, H47, H48, H57, H59, H77, H78, H79, H85, H86, H87, H88, H89, H90

2)  This is indicated by the number of virtual channels, about 90 for the i100 and 120 for the HR90k; and manifests itself as more, and more closely spaced, pitch percepts. This is made possible by separate current sources for each electrode contact: The HR90k can fire both positive AND negative pulses simultaneously, while the i100 can fire multiple simultaneous positive OR negative pulses for basic current steering. To this day, even the new Nucleus 5 only has a single current source for all 22 contacts, as AB and MedEl have their technologies tightly wrapped up in worldwide patents.

3) 5/31/2012 correction: ClearVoice was approved by FDA in March 2012, not March 2010 as originally stated. The text has been changed to reflect this correction.

Wolfe, Jace, and Schafer, Erin C. 2014. Programming Cochlear Implants 2nd Edition. San Diego: Plural Publishing. ISBN-13: 978-1-59756-552-3 ISBN-10: 1597565520

Wolfe, Jace, and Schafer, Erin C. 2010.  Programming Cochlear Implants 1st edition.  San Diego: Plural Publishing. ISBN-13 978-1-59756-372-7

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About the author

Dan Schwartz

Electrical Engineer, via Georgia Tech

7 Comments

  1. Jeffrey Simmons
    June 5, 2012 at 10:06 pm

    In reference to your comment about the notable absence of a Greenwood tonotopic map (which implies that it was important to have included it), it warrants mentioning that it is my impression that most serious CI researchers at the current don’t consider the Greenwood model to be especially accurate with regard to CI recipients. Greenwood’s map assumes stimulation at the level of the hair cells/organ of corti. A cochlear implant, as we know, stimulates neural tissues (dendrites and the spiral ganglion cell bodies), not hair cells. An examination of cochlear anatomy shows us that neural structures in the cochlea don’t have the same relationship to distance along the cochlea that hair cells have. Rosenthal’s canal, through which neural fibers pass from modiolus to the organ of Corti, does not extend to the apical turn of the cochlea and is not linearly related to that organ. Even putting that argument aside, it is my understanding that application of Greenwood’s function relies on knowledge of the actual length of the organ of Corti. This is reportedly difficult to do through most imaging studies, and evidence in the past few years supports the idea that there is significant individual variability in cochlear dimensions…moreso than might have been assumed in the past. So while a Greenwood map might be generally illustrative of an overall concept of tonotopic organization, it can’t really be reliably applied to any given CI recipient. Based on that, I wonder if its absence in the work in question is really that notable.


    • Dan Schwartz
      June 14, 2012 at 1:50 pm

      Although what you say is pretty well true, and would pertain to student and practicing audiologists, please note that we also recommended it for a college educated CI candidate, CI “power user,” or even the parents of a “CI kiddie,” as it provides a nicely detailed view of CI’s. In fact, the Greenwood map we used in the article is from the old Med-El website before their site redesign, and it provides an intuitive feel for what is (approximately, as you point out) occurring when electrical stimulation is applied.

      In a private communication, Dr Wolfe has said he indeed will be incorporating my suggestions into a future, second edition

      We have forwarded your excellent comment on to Dr’s Wolfe & Schafer for their comments as well.

      Dan Schwartz,
      Editor


    • Dan Schwartz
      October 14, 2014 at 4:24 pm

      Ben & Jeffrey, in looking again at your replies from two years ago, I’m curious as to whether what you state about the lack of correlation between acoustic tonotopic mapping and electrical stimulation is due to the charge “cloud” effect from the inability of the Cochlear & Med-El implant circuits to simultaneously fire positive & negative charges over 3-4 electrodes to “focus” the charge into a beam (think of a phased RADAR array), where it will stimulate far fewer dendrites in the spiral ganglion.

      The reason I say this is based on the anecdotal observations by Daniela Andrews in Cochlear Implant Channel Crossover: First Person Report, and by Mike Marzalek on his CItheory.com website.


  2. Benjamin A. Russell
    June 21, 2012 at 10:30 am

    I agree, this is a great book. It is actually the one that my research mentor uses for her CI Audiology class. It is very up-to-date, and as you mentioned, easy to digest. I am working this summer as a clinical supervisor for our Au.D. program, and I use this book to go over various concepts that our student clinicians may not be familiar with, since they have not had the formal CI course yet.

    In regards to the Greenwood map conversation, I agree with Mr. Simmons that it may be best to just generally reference tonotopic organization. However, some serious CI researchers do indicate that the Greenwood place-pitch map is maintained for CI listeners (Carlyon et al., 2010; Vermeire et al., 2008). Others looking at that issue indicate that with enough time, CI listeners are able to adapt and perceive pitches more closely related to their electric maps (see work by Riess et al. for review).


  3. Mohamed Wael M. Mustafa
    July 9, 2015 at 5:04 pm

    Dear Dan,
    I have already ordered a copy of this book. I bought it to teach my postgraduate students CI programming techniques. Will it really help?

    Best regards,

    Mohamed Wael


    • Dan Schwartz
      July 10, 2015 at 12:53 pm

      Dr Wael, it sure will help you teach your students; and their copies will be a nice desktop reference.

      ▬▬► Be sure to get the second edition.


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