The Link between Diabetes Mellitus and Sensorineural ... · Mellitus and Sensorineural Hearing Loss How Open Canal Amplification Was Discovered. ... “The Link between Diabetes Mellitus

Vol. 9 No. 12014

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The Link between Diabetes Mellitus and Sensorineural Hearing Loss

How Open Canal AmplificationWas Discovered

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Welcome to another stellar year of CanadianHearing Report. Now that I’ve set the bar reallyhigh for 2014, all I have to do is deliver thegoods. You might think this may not be an easyfeat considering the outstanding contributors wehad in 2013, but it’s important to aim high; withthe lineup we have for this issue, I think we pullit off.

Right off the bat, we’ve got the Happy HoHcolumn from the always entertaining andinformative consumer advocate Gael Hannan,who shares with us the “Easy Lessons of HearingLoss.”

Also, with kind permission from the fine folks atHearingHealthMatters.org, this issue includes anarticle by Robert Traynor discussing who hethinks is the “Real Father of Audiology.”

We are also happy to bring you a brand newcolumn called Shop Talk. This issue’s Shop Talksees CHR sitting down with Unitron’s Rob Walesato discuss Unitron’s exciting new Flex program.

Not to be outdone, the issue’s features are must-reads as well. First up is James Curran’s excellent“How Open Canal Amplification WasDiscovered,” followed by a terrific article fromEirini Mihanatzidou and Rhonda Kerlew called“The Link between Diabetes Mellitus andSensorineural Hearing Loss.”

What a great way to start the New Year! Pleaseenjoy the issue.

Scott BryantManaging EditorCanadian Hearing Report 2014;9(1):3.

MESSAGE FROM THE MANAGING EDITOR |

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ACCOUNTING / COMPTAB IL ITÉ

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contentsSteve Aiken, PhD, Dalhousie University

Alberto Behar, PEng, Ryerson University

Leonard Cornelisse, MSc, Unitron Hearing

Joanne DeLuzio, PhD, University of Toronto

Lendra Friesen, PhD, Sunnybrook Health Sciences Centre

Gael Hannan, Hearing Loss Advocate

Bill Hodgetts, PhD, University of Alberta

Lorienne Jenstad, PhD, University of British Columbia

André Marcoux, PhD, University of Ottawa

Sheila Moodie, PhD, University of Western Ontario

Calvin Staples, MSc, Conestoga College

Rich Tyler, PhD, University of Iowa

Michael Valente, PhD, Washington University

Follow us on Twitter @chr_info

Scott Bryant, James Curran, Rhonda Kerlew,Gael Hannan, Eirini Mihanatzidou, Robert Traynor

COLUMNS18 FOUNDERS OF AUDIOLOGY EARL HARFORD

FEATURES RESEARCH AND DEVELOPMENT FOCUS

21 How Open Canal Amplification Was Discovered BY JAMES R CURRAN, MS

24 The Link between Diabetes Mellitus and Sensorineural Hearing Loss: A Summary of the Evidence BY EIRINI MIHANATZIDOU, MA(HONS), M.AUD, AUD(C),

REG. CASLPO, AND RHONDA KERLEW, RN, BSCN, MBA

DEPARTMENTS3 Message from the Managing Editor

COLUMNS6 FROM THE BLOGS@ HEARINGHEALTHMATTERS.ORG

9 SHOP TALK What If There Was a Way to Remove the Pressure and Uncertainty for First-Time Hearing Instrument Purchases?

10 THE HAPPY HOH The Easy Lessons of Hearing Loss BY GAEL HANNAN

12 NEW ON THE SHELVES Sandin’s Textbook of Hearing Aid Amplification: Technical and Clinical Considerations, Third Edition

Handbook of Central Auditory Processing Disorder Volume 1: Auditory Neuroscience and Diagnosis, Second Edition Hearing in Children, Sixth Edition

Programming Cochlear Implants, Second Edition


6 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION

| FROM THE [email protected]

WHO IS THE REAL “FATHEROF AUDIOLOGY”By Robert TraynorPosted March 13, 2013

Around the world there is usually oneindividual that stands out as the personthat began the profession of audiologyin their respective country. These areoften those that came to the US, or inlater years, other countries asinternational students and took theprofession home and began its practice.These individuals are often thought tobe the “Father or Mother of theprofession” in their part of the world.There are many individuals that have

taken the field and spread it across theglobe serving the hearing impaired. OurHearing International quest this weekis to review the beginnings of audiologyto find that person that began theprofession or became the true “Fatherof Audiology”.

As professions evolve, audiologydeveloped rather rapidly. With roots inthe speech sciences of the 1920s and1930s and the basics of audiometry byC.C. Bunch, the profession really got itsstart during World War II in thetreatment of hearing impairedAmerican veterans. Newby (1958)presents that the first use of the word

Audiology has been traced to Trainorand Hargrave (1939). The termaudiology, however, did not get regularuse until 1945 when Raymond Carhart,then an Army speech pathologist andNorton Canfield, an Army otologistapplied the term to the field which hadbeen created through the tow fields ofspecialization that these menrepresented. Probably best historicaldiscussion of the development ofaudiology during the World War IIperiod is a 2002 Monograph toAudiology Today titled, “The Origins ofAudiology: American Wartime MilitaryAudiology,” by Dr. Moe Bergman.

Dr. Moe Bergman.

Dr. Bergman, along with his contem-poraries, lived the infancy of audiology.A time when there were many basicquestions and very few answers aboutauditory evaluation and rehabilitativetreatment of the hearing impaired.Bergman’s treatise reads like a virtual“Who’s Who” of speech and hearing in

the 1950s, 60s, and 70s and should beon the reading list for every basicaudiology course worldwide. It was thisgroup of audiology pioneers and theirclinical experiences, developed in theshadows of War, that shaped theprofession in their publications,textbooks, teaching, research, andleadership that molded audiology into arobust, research-based, clinicalprofession.

While these professionals developedtheir skills during the War, the postwarperiod marked the advent oftremendous technological growth, the

use of transistors and such that led to thedevelopment of tools for assessing thelevels of sound individuals were exposedto, degrees of hearing loss, and in thedevelopment of smaller hearing aids.While all of these pioneers substantiallycontributed the development of theprofession one individual, Dr. RaymondCarhart, clearly stands out as theundisputed worldwide “Father ofAudiology”. This week HearingInternational focuses on Dr. RaymondCarhart (1912-1975), lest we forget ourroots.

Raymond T. Carhart.Courtesy of theNational Library ofMedicine.

Raymond Thomas Carhart was born onMarch 28, 1912, in Mexico City, son of

Raymond Albert and Edith (Noble)Carhart. There is not much publicinformation as the Dr. Carhart’schildhood and early education but hereceived a bachelor of arts degree inspeech and psychology from DakotaWesleyan University in 1932, and wenton to finish master’s of arts (1934), anddoctor of philosophy (1936) degrees inspeech pathology, experimental phonetics

and psychology at NorthwesternUniversity. A student of CC Bunch, hewas one of Northwestern’s first PhDgraduates — in speech pathology,experimental phonetics, and psychology.

Dr. Carhart remained at Northwesternwith the title of instructor in speech re-education from 1936 to 1940. In 1940he was promoted to assistant professor

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and in 1943 to associate professor. Thefollowing year he joined the MedicalAdministrative Corps, U. S. Army, as acaptain, ultimately serving 7 years.During the War, Dr. Carhart served asdirector of the Acoustic Clinic and asacoustic physicist at the until 1946.One of the three facilities designated forhearing rehabilitation during the Warperiod. After World War II, he thenreturned to Northwestern where hebecame professor of audiology in 1947,a position he held until his suddendeath on October 2, 1975. In 1948Carhart was appointed assistantprofessor of otolaryngology at theMedical School in recognition of hiswork on the Chicago Campus; he wasmade a full Professor in 1952.

He may be best known for developingand refining speech audiometry, themeasure of hearing ability, particularlyas it pertains to the efficiency of hearingaids. Most of us remember the “CarhartMethod” of hearing aid evaluation thatwas the “tried and true” technique forabout 40 years. While this method wasproven to be unreliable and invalid inthe 1980s, the technique offeredextreme face validity and patients stillask why we do not do this type of anevaluation for hearing aid fittings today.

Although his life was cut short, he haslived on through his many students that

became the pillar of the profession,conducting their own research, writingthe textbooks, direct audiologyprograms, founding associations, such asthe Academy of Dispensing Audiologists(recently changed to the Academy ofDoctors of Audiology), AmericanAcademy of Audiology and the Academyof Rehabilitative Audiology. His studentsbecame, generally, the teachers of myaudiology generation.

As a student or a professional, I did nothave the opportunity to meet Dr.Carhart, but I have had the opportunityto meet and work with a number of hisstudents that have carried on his legacy.One of my favourite Carhart quotes ispart of his introduction to MikePollack’s first edition of Amplificationfor the Hearing Impaired in 1975 and itsuggests his love of the clinic and thosethat practiced the profession.

“The researcher can gather factafter fact at his leisure until he hasa sufficient edifice of evidence toanswer his question with surety.How different is the clinician’s task.He too, is an investigator but thequestion before him is, “What canI do now about the needs of theperson who is seeking my help atthis moment?” The clinicianproceeds to gather as much data aspossible about his client as he can

in a clinically reasonable period oftime. He does not have the luxuryto wait several months or years forother facts to appear. Thedecisions of the clinician are moredaring than the decisions of theresearcher because human needsthat require attention today impelclinical decisions to be made morerapidly and on a basis of lessevidence than do researchdecisions. The dedicated andconscientious clinician should bearthis fact in mind proudly. His isthe greater courage.”

In the words, of Dr. Jay Hall, another ofCarhart’s students, “stumbling intoNorthwestern University [circa, 1972]was one of the luckiest breaks in mylife. The students were top notch, theacademic setting stimulating and, bestof all, I was among a Who’s Who inspeech pathology and audiology. I wasassigned reception desk duty to earnmy stipend and each day I had theopportunity to greet the notables whoentered the then new Francis SearleBuilding, including the Father ofAudiology – Raymond Carhart.”

REFERENCENewby H. Audiology. New York: Meridith

Corporation; 1958.

Canadian Hearing Report 2014;9(1):6-8.

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SHOP TALK |


What If There Was a Way to Remove thePressure and Uncertainty for First-Time

Hearing Instrument Purchases?

CHR: Why is a program like Flex importantin today’s hearing health care market?

Rob Walesa: Our customers are facing manychanges in the market. Their neighbourhoodis becoming increasingly crowded. Theymust respond to aggressive, price-orientedmarketing campaigns. And, they are dealingwith a more sophisticated and educatedcustomer. Flex is a perfect opportunity for usto help our customer tackle these challengesby differentiating themselves; changing thediscussion with their patient; and addressingnew wearers in a very different way.

CHR: How is Flex allowing clinicians tochange the conversation with their patients?

RW: If a person is on the fence about theirhearing loss, and is skeptical about the needfor amplification, it can be difficult for aclinician to move them past this barrier. Untilthey can experience the benefit ofamplification directly, they cannot place avalue on it. They put more emphasis onprice and go into commodity mode. Flexallows a clinician to change that conversationby allowing that new patient to “‘test drive”’amplification specifically suited to theirneeds, right at the first appointment. Whena consumer experiences the benefit of

amplification, it increases their understandingof the value.

CHR: What value does this alteredconversation bring to the clinician?

RW: Flex allows clinicians to really practicetheir craft; helping people to make betterdecisions about their hearing health.Clinicians who have adopted Flex:trial™ tellus that they are having more productivediscussions with their patient. Theconversation is focused on understandingthe impact hearing loss is having on their life;rather than selling products. This also helpspatients see the clinical benefit and perceivethe hearing health care provider as aprofessional offering an important service.

CHR: Do you believe this concept can helpto increase hearing aid adoption for newusers?

RW: Yes, that is overall premise for Flex. Itnot only addresses the barrier to adoption;it is an important source of differentiation forclinics in a very crowded neighborhoodwhere there is a lot of competitive pressurearound them, and businesses are playing theprice card. It is also very valuable for clinicswith a high level of referral traffic, because it

changes up the selling process for newwearers. A clinician can say, “If people comeand present with loss, we’ll give them a testdrive and an opportunity to experienceamplification and the way it fits into their life– at no risk, and with no upfront financialcommitment. “This elevates the credibility ofthat clinician, and reflects well on the personwho has referred the client. That’s a hugedifferentiator.

CHR: Flex is also an upgradeable hearingaid. What has customer reaction been tothis offering?

RW: Flex:upgrade™ allows the clinician toenhance the patient’s ownership experience,by allowing them to improve theirperformance without having to push reset onthe hardware. Typically the upgrade programis discussed with a client after the purchaseas part of the ongoing support they canexpect. It allows a clinician to say, “I wouldlike to see you for follow-up appointmentsto ensure the technology is addressing yourneeds, and if down the road, you, or Idetermine you need more, we can easilyapply an upgrade.”Canadian Hearing Report 2014;9(1):9.

Unitron’s Flex™ program is the industry’s first risk-free hearing instrument trial andupgrade solution aimed at reducing the barriers to hearing aid adoption. WithFlex:trial™, hearing health care professionals can fit patients with a same day trial oftechnology they recommend, at no cost or obligation, allowing them to experience thebenefits of hearing instruments in their daily lives.

One year after the Flex program’s introduction, Canadian Hearing Report catches upwith Rob Walesa, General Manager, Unitron Canada to talk about the market’s reactionto Flex, and the advantages it brings to clinicians and their patients.


| THE HAPPY HoH

About the AuthorGael Hannan is a writer, actor, and public speaker who grew up with a progressive hearing loss thatis now severe-to-profound. She is a director on the national board of the Canadian Hard of HearingAssociation (CHHA) and an advocate whose work includes speechreading instruction, hearingawareness, workshops for youth with hearing loss, and work on hearing access committees.

Gael is a sought-after speaker for her humorous and insightful performances about hearing loss.Unheard Voices and EarRage! are ground-breaking solo shows that illuminate the profound impactof hearing loss on a person’s life and relationships, and which Gael has presented to appreciativeaudiences around Canada, the United States and New Zealand. A DVD/video version of UnheardVoices is now available. She has received several awards for her work, including the ConsumerAdvocacy Award from the Canadian Association of Speech Language Pathologists and Audiologists.Gael lives with her husband and son in Toronto.

Welcome to the first issue ofCanadian Hearing Report for 2014

and to the Happy HoH, a column thatexplores the life with hearing loss.(Note: HoH is an acronym for Hard ofHearing – and it sounds like it looks.So, I’m careful not to identify myself asa HoH when I go to the store, becauseI’m looking for milk, not trouble.)

I’ve lots of experience being a HoH –since birth, apparently. I live andbreathe the barriers and challenges ofhearing loss. As an advocate, I talkabout the communication strategiesthat can break them down. Are theyeasy? Do I use all the strategies,regularly, that can help me to succeedin the constant presence of hearingdifficulties?

Please, I’m only human!

Just because I know what’s good for medoesn’t mean that I actually practice itwith every word I listen to, or speak.Life with hearing loss is complex, andto communicate well requires a big bagof tricks that involve emotions, endlesshours of effort and more than a fewdollars of hard-earned money. Andalthough I often slip into some badcommunication habits, I think after afew decades, I’ve more or less got itdown to a fine art.

It’s just not always easy. Mind you, somethings are…

It’s EASY to convince ourselves thatwe’re doing “fine” with our hearing loss:

That we’re catching most of what’ssaidWell, at least the important stuff –

the rest’s not really worth listeningto, right?

And no, we don’t intend to doanything about itLike getting a hearing aid orcochlear implant –

Those are for other people, whohave real problems.

It’s EASY to give in to frustration and theemotional roller coaster of hearing loss:

Because nothing has ever preparedus for this –This…invisible separation…from

the life we’re used to,And the people we were close to.It’s like standing outside, looking

through a windowRapping on the glass and trying to

talk to our family on the inside.It hurts.

The Easy Lessons of Hearing Loss

By Gael [email protected]

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It’s EASY to slip into bad habits ofbluffing, of tuning out:

Because we just can’t get what’s being said,

Even though we’re trying so hard to follow.

It makes us tiredAnd before we even realize it,We’re nodding and smiling as if

we’re totally in the conversationAnd we hope no one calls us on it.Because we would be embarrassed

– and they would be irritated.

It’s EASY to blame other people forcommunication breakdowns:

“They won’t face me, They forget all the time, They just…they just don’t

understand.Even though I’ve explained itOver and over again.I’ve done all I can and now it’s up

to them.Hell, I’m the one with the damn

hearing loss!How about a little consideration?”

It’s EASY to blame our hearing loss foreverything that’s not going right:

“My marriage would be better if itwasn’t for my hearing

My kids wouldn’t laugh or take advantage of me

I would be happier at work,I’d feel better about myselfAnd I could focus my energy on

making things better Instead of using it all upOn trying to communicate, Or even hiding it completelyAnd don’t tell me that’s wrong, thatI shouldn’t do it – I’d like to see you struggling every

day, all day,With hearing loss like mine.”

It’s EASY to let hearing loss define us:

Life was better before.Now it’s not.My hearing loss affects everything, Everything I do, everyone I talk to.I am my hearing loss.

No one ever said that being a HoH iseasy. But it doesn’t have to be this hard,either.

We – all of us – have bad hearing dayswhen we want to crawl into bed, pullthe covers over our head, and cry infrustration over the relentless pressure

of communication gone wrong. But ifwe stay in hiding, if we keep crying,our negative attitudes will harden intocement and we won’t be able to breakfree.

There’s another easy lesson if we wantto take it: help is available, standing by,waiting. If you – or anyone you know– is struggling with hearing loss, reachout for help. Read this magazine andother publications. Speak to yourdoctor or visit a hearing careprofessional. Contact a hearing lossgroup in your community, or online,where there are people with hearingloss who understand what you’re goingthrough. They can help, because they’vebeen there, too.

Reach out. It’s the easiest lesson ofhearing loss.

Here’s to the new Allied Hearing Healthmagazine! When you’re done reading,pass it along, because you probablyknow someone else with hearing losswho needs help, too.Canadian Hearing Report 2014;9(1):10-11.


| NEW ON THE SHELVES

SANDIN’S TEXTBOOK OF HEARING AID AMPLIFICATION:TECHNICAL AND CLINICAL CONSIDERATIONS, THIRD EDITIONEdited by: Michael J. Metz

ABOUT THE BOOKThe comprehensive Sandlin's Textbook of Hearing Aid Amplification, now inits third edition, provides the hearing health professional with an overview ofthe technological advances related to hearing aid devices. The authors giveparticular emphasis to the most current advances in clinical assessmenttechniques and hearing instrument technology, and provide a detailed analysisof the application of digital signal processing. Clinical insights into thepsychology of hearing health are included to help professionals meet clients’emotional as well as acoustic needs. This is a valuable text for academic andclinical professionals involved in the selection and fitting of hearing aid devicesfor the acoustically impaired.

New to the third edition:

• Updated chapters on earmold and earshell acoustics; principles and applications of high-fidelity amplitude compression; and microphone technology

• Major revisions to chapters on digital signal processing; hearing aid selection, fitting, and verification; mathematical formulae for applying amplification; measures of validity and verification; and surgically-implanted hearing devices for unilateral hearing loss

• Discussion of distribution methods; considerations for treating children;elements of design and implementation of DSP circuits; the evolution from analog to digital hearing aids; and future consideration for the field

This text is regularly used by clinicians at the graduate level of training in the70 to 90 universities offering graduate degrees in audiology. Furthermore,practicing clinicians in countries all over the world have included thisrecognized text in their professional libraries.

CONTENTSForeword by Michael J. MetzPrefaceAcknowledgementsContributors

1. A Historical ViewSamuel F. Lybarger, Edward H. Lybarger

2. Speech Perception and Hearing AidsWilliam H. McFarland, Karen Spayd

3. Custom Hearing Aid Earshells and EarmoldsChester Z. Pirzanski

4. Principles of High-Fidelity Hearing Aid AmplificationMead C. Killion, Patricia A. Johnson

Feb. 2014 • 800 pages • Illustrated (B/W)Softcover • 8.5 x 11" / 279 x 216 mm. ISBN13: 978-1-59756-563-9$159.95 / £126.00

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5. The Many Faces of CompressionTheodore H. Venema

6. Use of Directional Microphone Technology to Improve User Performance in NoiseYu-Hsiang Wu, Ruth A. Bentler

7. DSP Hearing InstrumentsIngo Holuba, Henning Puder, Therese M. Velde

8. From Analog to Digital Hearing AidsSøren Westermann, Hanne Pernille Anderson, Lars Bækgaard, et al.

9. Technical Considerations for Sound Field AudiometryGary Walker

10. Psychology of Individuals with

Hearing ImpairmentRobert W. Sweetow, Julie Bier

11. Considerations for Selecting and Fitting of Amplification for Geriatric AdultsRobert E. Novak

12. Hearing Technology for ChildrenJace Wolfe, Sara Neumann

13. Principles and Clinical Utility of Hearing Aid Fitting FormulasPhillip T. McCandless

14. Real Ear MeasuresGeorge Frye

15. Making Hearing-Aid-Fitting DecisionsRobert L. Martin

16. Inventories of Self-Assessment

Measurements of Hearing Aid OutcomesJudy L. Huch

17. Assistive Technologies for the Hearing ImpairedJoseph J. Smaldino, Brian M. Kreisman

18. Cochlear ImplantsDawn Burton Koch, Mary Jo Osberger

19. Fitting Options for Adult Patients with Unilateral Hearing LossMichael Valente, L. Maureen Valente

20. Future ConsiderationsMichael J. Metz, Robert E. Sandlin

Appendix A: American Academy ofAudiology Ethical Practice Guidelinefor Relationships with Industry


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HANDBOOK OF CENTRAL AUDITORY PROCESSING DISORDERVOLUME 1: AUDITORY NEUROSCIENCE AND DIAGNOSIS,SECOND EDITIONEdited by: Frank E. Musiek, PhD and Gail D. Chermak, PhD

ABOUT THE BOOKMusiek and Chermak’s two-volume, award-winning handbooks are back innewly revised editions. Extensively revised and expanded, Volume I providescomprehensive coverage of the auditory neuroscience and clinical scienceneeded to accurately diagnose the range of developmental and acquired centralauditory processing disorders in children, adults, and older adults. Volume IIprovides expanded coverage of rehabilitative and professional issues, detailingintervention strategies for children and adults.

Building on the excellence achieved with the best-selling 1st editions—whichearned the 2007 Speech, Language, and Hearing Book of the Year Award—the second editions include contributions from world-renowned authorsdetailing major advances in auditory neuroscience and cognitive science;diagnosis; best practice intervention strategies in clinical and school settings;as well as emerging and future directions in diagnosis and intervention.

Exciting new chapters for Volume I include:

• Development of the Central Auditory Nervous System, by Jos J. Eggermont

• Causation: Neuroanatomic Abnormalities, Neurological Disorders, and Neuromaturational Delays, by Gail D. Chermak and Frank E. Musiek

• Central Auditory Processing As Seen From Dichotic Listening Studies, byKenneth Hugdahl and Turid Helland

• Auditory Processing (Disorder): An Intersection of Cognitive, Sensory,and Reward Circuits, by Karen Banai and Nina Kraus

• Clinical and Research Issues in CAPD, by Jeffrey Weihing, Teri James Bellis, Gail D. Chermak, and Frank E. Musiek

• Primer on Clinical Decision Analysis, by Jeffrey Weihing and Sam Atcherson

• Case Studies, by Annette E. Hurley• The CANS and CAPD: What We Know and What We Need to

Learn, by Dennis P. Phillips

CONTENTS Section 1: Auditory NeuroscienceChapter 1. Auditory Neuroscience and Central Auditory Processing

Disorder: An Overview Frank E. Musiek & Gail D. Chermak

Chapter 2. Psychoacoustic Considerations and Implications for the Diagnosis of Central Auditory Processing Disorder Raymond M. Hurley & Annette E. Hurley

Nov. 2013 • 768 pages • Illustrated (B/W)Hardcover • 7 x 10" ISBN13: 978-1-59756-561-5£79.00 / $99.95

Chapter 3. Development of the CentralAuditory Nervous SystemJos J. Eggermont

Chapter 4. Neurological Substrate of Central Auditory Processing Disorder Gail D. Chermak & Frank E. Musiek

Chapter 5. An Introduction to CentralAuditory NeuroscienceDennis P. Phillips

Chapter 6. Central Auditory ProcessingAs Seen From Dichotic Listening StudiesKenneth Hugdahl & Turid Helland

Chapter 7. Auditory Processing Disorder: An Intersection of Cognitive, Sensory, and Reward CircuitsKaren Banai & Nina Kraus

Chapter 8. Nature of Central AuditoryProcessing DisorderTeri James Bellis

Chapter 9. Clinical and Research Issuesin Central Auditory Processing DisorderJeffrey Weihing, Teri James Bellis, Gail D. Chermak, & Frank E. Musiek

Section 2 Diagnostic FundamentalsChapter 10. Screening for Central

Auditory Processing DisorderWayne J. Wilson

Chapter 11. Test Battery Principles andConsiderationsJane A. Baran

Chapter 12. Primer on Clinical Decision AnalysisJeffrey Weihing & Samuel R. Atcherson

Section 3: Evaluation of CentralAuditory ProcessesChapter 13. Monaural Low-

Redundancy Speech TestsSridhar Krishnamurti

Chapter 14. Dichotic Listening TestsJeffrey Weihing & Samuel R. Atcherson

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HEARING IN CHILDREN, SIXTH EDITIONJerry L. Northern, PhD and Marion Downs

ABOUT THE BOOKIn this completely updated sixth edition, Hearing in Children thoroughlyexamines the current knowledge of pediatric audiology, and provides a medicalperspective on the identification, diagnosis, and management of hearing lossin children. This enduring text, written by two universally recognized pediatricaudiologists, has been the chief pediatric hearing resource used worldwide byaudiologists for nearly 40 years.

Key features to Hearing in Children, Sixth Edition include:

• An expanded review of the medical aspects—early intervention, genetics,diseases and disorders, and treatments—of pediatric hearing loss as wellas hearing and auditory disorders in infants, toddlers, and young children

• Practical descriptions of age-specific testing protocols and hearing screening technologies, and early hearing loss detection and interventionprocedures

• Comprehensive coverage of amplification for children with hearing loss,including fitting and management issues in hearing aids, cochlear implants, and assistive listening devices

• Valuable information on the role of family-centered services related to all aspects of childhood deafness

• A revised appendix of hearing disorders that includes 90 syndromes anddisorders associated with childhood deafness

• Nearly 500 new and current references

CONTENTSDedicationPreface: Jerry L. Northern, PhDForward: Marion P. Downs, DHS, DSAcknowledgementsChapter 1: Hearing and Hearing Loss in ChildrenChapter 2: Early DevelopmentChapter 3: Auditory and Speech-Language DevelopmentChapter 4: Medical AspectsChapter 5: Early InterventionChapter 6: Behavioral Hearing TestsChapter 7: Physiologic Hearing TestsChapter 8: Hearing ScreeningChapter 9: AmplificationChapter 10: Education Appendix i: Pediatric Hearing Disorders Appendix ii: Guidelines for Identification and Management of Infants andYoung Children with Auditory Neuropathy Spectrum Disorder

Mar. 2014 • 345 pages • Illustrated (B/W)Hardcover • 7 x 10" / 254 x 178 mm. ISBN13: 978-1-59756-392-5$99.95 / £79.00

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PROGRAMMING COCHLEAR IMPLANTS, SECOND EDITIONEdited by: Jace Wolfe, PhD and Erin Schafer, PhD

ABOUT THE BOOKCochlear implants offer significant benefits for children and adults with severeto profound hearing loss; however, to realize these benefits the device mustbe carefully and correctly programmed. With current information on cochlearimplant technology, Programming Cochlear Implants, Second Edition—a volumein the Core Clinical Concepts in Audiology Series—is a valuable guide forclinicians providing services to cochlear implant users or as a teaching toolfor graduate-level students.

Programming Cochlear Implants, Second Edition introduces the basics of cochlearimplant hardware and programming and continues through advancedprogramming techniques, with manufacturer-specific information and casestudies. The text reviews clinical protocols for cochlear implant management;programming considerations for bilateral cochlear implant; troubleshootingduring the programming process; device-specific programming techniques;use of objective measures to set cochlear implant programs; use of FM andassistive listening devices with cochlear implants; and providing support todifficult-to-program users, such as infants, cognitively-impaired individuals,persons with disabilities, and so forth.

New topics addressed in the second edition include:

• Preservation of residual hearing following cochlear implant surgery• Programming cochlear implants for patients with substantial residual

hearing in the low-frequency range, including electrode array options• Cochlear implant impedances and the impact of impedance on

programming and management• Signal coding strategies and signal processing• Theoretical concepts that may influence cochlear implant programmingCONTENTSForewordPreface Acknowledgments Basic Components and Operation of a Cochlear Implant Basic Terminology of Cochlear Implant Programming Basic Principles of Programming Manufacturer-Specific Programming Considerations Clinical Considerations: Putting All of the Pieces Together Troubleshooting Patient Complaints and Complications Hearing Assistance Technology (HAT) and Cochlear Implants Electroacoustic ProgrammingCase StudiesReferences IndexCanadian Hearing Report 2014;9(1):12-17.

Mar. 2014 • 200 pages • Illustrated (2 color)Softcover • 8.5 x 11" / 279 x 216 mm. ISBN13: 978-1-59756-552-3$59.95 / £48.00


| FOUNDERS OF AUDIOLOGY

CHR: When you hear the name EarlHarford one normally thinks of CROShearing aids. Specifically, Harford andBerry (1965) in the Journal of Speech andHearing Disorders was the article when Ifirst read about your work with what tobecome known as the CROS hearing aid.What led you to do work in this area?

Earl Harford: I worked in anaudiology/otolaryngology clinic that weheld once a week at NorthwesternUniversity in Chicago and there was anotolaryngologist that I worked withnamed George Shambaugh, adistinguished otolaryngologist and along-time editor of the Archives ofOtolaryngology.

One day we had a patient come in with aunilateral hearing loss. We counseledhim in the routine manner for at thattime delete there was nothing that couldbe done in a medical or surgical mannerand from the standpoint of using ahearing aid he was not a candidatebecause his good ear was too good andhis bad ear was too bad to make any

sense of amplified sound.

We told him he can compensate for thisto some degree by ensuring that his goodear is aimed towards the speaker and toseat where he would always favor hisgood ear – we discharged the patient inthe usual manner. Then Dr. Shambaughturned to me and asked whether I hadevery considered putting a microphoneon the bad ear and running apolyethylene tube around and sticking itin the good ear. That would carry thesound across the head. I hadn’t reallythought too much about that since therewould be too much loss of the higherfrequencies due to the presence of thislong tube.

I went back to Evanston, Illinois (theseclinics were always held in the medicalschool in Chicago) and I told Joe Barry,my grad assistant, about this and we bothlaughed and thought that this idea wouldnot work. After a few days of thinkingabout it, it occurred to me that we don’thave to use a tube – we could use a wire.

Perhaps I could get a couple of hearingaid companies to make such a device forme and we could do a little study on it. Ihad access to Zenith, Maico, and Beltoneat that time – Zenith and Beltone werehoused in factories in and aroundChicago at that time and it made it easy,and I had a good working relationshipwith Maico as well.

We tested quite a few people and itturned out that it really worked quite

well. In the Harford and Berry (1965)paper we emphasized that the bestsuccess was when a person had a highfrequency hearing loss in the good ear.Many people forget this and the greaterthe high frequency hearing loss that aperson would have in their good ear, themore difficulty a person would have incompensating for their unilateral hearingloss. Consequently the experience ofgreater benefit and also greateracceptance of the device was seen withthose who also had a high frequencyhearing loss in their good ear.

Another thing that we pointed out in the1965 article was that the more recent thehearing loss in the bad ear, the moreacceptance we had with the CROS aids.Conversely if a person is congenitallydeaf on one side, he becomes so adjustedto that, he won’t appreciate muchimprovement from the CROS aid. Stillwe had some people (even some withcongenital losses) who accepted theCROS and used it on a regular basis.

CROS hearing aids are still being used.Soon, we branched off from the originalCROS and did a lot of work withdifferent devices that sought to addressthe issue of imbalance between the twoears. These included a multitude ofnames and acronyms such as BICROS,HI-CROS and the power CROS Versionsof the CROS Hearing Aid. The powerCROS is really the same thing that RoySullivan referred to as the transcranialCROS.

An Interview with Earl Harford

Earl Harford

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Jim Curran (who was then with Maicoand later with Starkey) used to tell aromantic story of one of the first CROSaids that went from side to side with ablack headband – I believe that he was alawyer. After using it in court, the lawyerrefused to give it up. We had some peoplethat when we took the prototypes backfrom them they were really concernedand didn’t want to give them up.

Elizabeth Dodds was a speech pathologystudent and after taking my clinicalaudiology course, she switched over toaudiology. I then hired her as a clinicalsupervisor when she graduated. She wasa ballerina before she went intoaudiology, so this being her “secondcareer” meant that we were of acomparable age. In 1968 Elizabeth and Ipublished an article in the Journal ofSpeech and Hearing Research entitled“Modified Earpieces and CROS for HighFrequencyHearing Loss,”

At the time we were not aware, but itultimately stimulated some people tothink about open ear canal fittings. Wefollowed that up in 1970 with“Followup-Report on Modified Earpiecesand CROS for High Frequency HearingLoss,” (Elizabeth Dodds and EarlHarford, 1970, JSHR, Vol.13, #1, 41-43).

We still didn’t realize what an impact thatwould have on open canal fittings. JimCurran has pointed this out to me severaltimes and from that time on I alwaysvented as much as I could except underextreme circumstances with very severelosses.

I remember when I had students at theUniversity of Minnesota I told them step#1 was use binaural whenever possible;step #2 is to cut the lower frequencies;step #3 was vent as much as you can;and step #4 use in-the-ear fittings

because you were taking advantage of theauricle and the various structures of thepinna to amplify high frequency soundsprior to reaching the actual hearing aid.And to this day I would not change thosebasic four rules. I wear in-the-ear hearingaids to this very day and favour themover behind the ear hearing aidswhenever possible.

I received my master’s from Vanderbiltand then went to NorthwesternUniversity in Chicago for my PhD in1955. There were three faculty memberthere – Ray Carhart, Jim Jerger, and JohnGaeth. John Gaeth later went to WayneState.

After I completed my PhD studies, Imoved to Montreal, Quebec and joinedthe faculty at McGill University andestablished the Audiology Clinic at theRoyal Victoria Hospital in 1958. Afterabout a year in Canada, I was invitedback to the faculty at Northwestern andapparently to fill John Gaeth’s vacancy. Iwas a faculty colleague of RaymondCarhart for over 16 year. Jim Jergerstayed until 1961 then left for the VA inWashington, DC, and then down to theBaylor College of Medicine in Texaswhere he spent many years.

Tom Tillman was the next to come on tothe faculty and then Bill Rintelmann andalso Bill Carver came through the post-doctorate program there. Bill Rintelmannand Wayne Olsen both ultimately joinedthe faculty at Northwestern. Noel Matkincame from the University of Connecticut– we had a great faculty there for manyyears.

CHR: After moving from NorthwesternI understand that you moved toVanderbilt and later to the University ofMinnesota. You had some famousstudents at that time.

EH: Yes. Over the years I had some superstudents who ultimately contributedgreatly to the field – Jay Hall, BobJohnson, Deborah Hayes, Wayne Olsen,and Brad Stach to name just a few.

CHR:Let’s switch over to the fact thatmany people call you “Dr. Real EarMeasurement.” I guess that we can’treally talk about real ear measurementunless we mention the name of DavidPreves in the same breath.

EH: I started to work on real earmeasurement in 1975 which was my lastfull year at Northwestern University. Iwent to Vanderbilt on January 1, 1976but my last few months at NorthwesternDavid Preves and I got together andtalked about Knowles new, tiny (at thetime) microphones being placed in theear canal. I don’t know how it all beganbut it was David or myself that thoughtabout putting the actual microphone inthe ear canal. Later, Starkey called thisthe RE-4 and was marketed in the midto late 1980s as a probe microphone(and not a probe tube microphone).

CHR:I recall that up to 3000 Hz the RE-4 was actually quite good but above that(due to the physical volume of themicrophone itself and the fact that itcould turn sideways in the ear canal) thehigher frequencies were suspect.

EH: It was pretty crude – themicrophones were large and we had touse rather crude equipment. When I leftNorthwestern, I went to Vanderbilt andbecame an administrator. I became thedirector of the Bill Wilkinson Hearingand Speech Center and Head of theDivision of Hearing and Speech Sciencesso I was a busy guy pushing papers andsolving people-problems. I didn’t do anyresearch while at Vanderbilt but I didwrite some articles while I was there.


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One was with Jennifer Fox called “TheUse of High-Pass Amplification forBroad-Frequency Sensorineural HearingLoss,” where we emphasized theimportance of cutting the lowerfrequencies for people with flatsensorineural hearing loss.

I ultimately married Jennifer Fox and sheand I have been married for 35 years.Actually Jennifer followed a similar pathas Elizabeth Dodds and she eventuallybecame my graduate assistant but I neverreally got to know her until about fiveyears after she left the program. I see herevery day now and we only talk aboutthe benefits of high pass amplification …(just joking, we also talk about otherthings).

Then when I went to Minnesota I was10-15 minutes away from David Prevesat Starkey and we had a regular pipelineof these miniature microphones. Wewere ruining the microphones everycouple of days and at first we didn’tunderstand it. It turned out that therewas a build-up of an electro-static chargeon them by walking across a carpetedfloor in the sound rooms.

I ran over 8000 measurements in theMedical School Audiology Clinic becausewe had a lot of patients there. Theequipment was working very well andwe were able to collect a lot of data – Ifelt like Jim Jerger! If you had yourprotocol set up correctly you couldgather a lot of data.

The first article that actually appeared inEar and Hearing in 1980 but the firstpaper I wrote wasn’t actually publisheduntil several years later in theproceedings of a University of Minnesota

conference on sensorineural hearing loss,tinnitus and vertigo held in September1979.

The most inspiring thing happened aftermy presentation. Dr Hallowell Davisattended the symposium delete and toldme that I was on the right track and weshould have been looking at this manyyears ago. He was the senior author ofthe first text book of audiology (Hearingand Deafness, A Guide for Laymen) thatI had studied back when I was 20 yearsold. I’ll never forget his words ofencouragement.

CHR: I understand that other than beingDr. CROS and Dr. Real EarMeasurement, you were also known asDr. Tympanometry?

EH: I did some early work ontympanometry with Gunnar Liden fromSweden. He and I were very closecolleagues and we had spent somesabbaticals together.

When I was at Northwestern he cameover and spent 15 months and hebrought with him the notion oftympanometry from Sweden (based onthe work of Henry Anderson andKlockoff at the Karolinska Institute ofTechnology [KTH]).

To digress, we used to ski together andone day we were discussing what otherwork we could do together so that hecould have a reason come back to theStates to work (and ski). On a chair liftin Utah we discussed the BAHA that hewas doing some work with AndersTjellstrom at the University ofGothenburg and we thought that wewould develop this. Ultimately he spent

two years at the University of Minnesotawhere we did early research on BAHA(1983–1985).

To come back to tympanometry in themid 1960s at Northwestern we had touse two bottles of water mounted on awall rack and we would move them upand down for high pressure and lowpressure while a tube was connected toa subject’s ear canal. Electronicmanometers were not available to us. Wenever did actually publish an article onthat unfortunately. We were preoccupiedon trying to get the apparatus to work,but we did run some very earlytympanograms.

Audiology was so romantic back thendelete. I never remembered a day Iresented going to work. In the early yearswe had to do everything by hand. Forexample, my first 80–90 publicationswere done without a computer they allhad to be done on a typewriter with noerrors and had to be submitted withcarbon copies.

I took my first course in audiology atFlorida State University in 1950 andnever looked back. I was about 20 yearsold then. I’ve been in audiology for about62 years now and I’ve seen a lot ofchanges. It’s been a whole lot of fun.

CHR: It’s been a pleasure talking to you.Thank you for your contributions to thefield.Canadian Hearing Report 2014;9(1):18-20.

RESEARCH AND DEVELOPMENT FOCUS |


If you were asked to name the mostsignificant developments in hearing

aids over the last fifty years, which oneswould you consider? Digital signalprocessing? The custom ITE/ITC family?The directional microphone? First fitalgorithms? Technologies for feedbackcontrol? They are all very worthy ofinclusion, but there are those who wouldplace the introduction of CROSamplification very near the top of thatlist. In point of fact, the CROS concept,introduced over fifty years ago, was theimpetus for a revolution in the thinkingof hearing care professionals of the day,and it spawned any number ofunderstandings over the next decadesthat remain an influence in our modernapproach to fitting.

Recall that CROS is an acronym forContralateral Routing of Signals, ahearing aid system first recommended(and still fitted today) for unilateral

hearing losses where the patient’shearing is good on one side and a loss ison the other. Originally conceived foruse with eyeglass aids, a microphone inthe temple of the unaidable side pickedup the signal that was transmitted by athin wire/cord connected to the circuitryand receiver in the other temple. Theamplified sound was delivered by atubing to an open ear, obviating the useof standard earmolds. Later, the industrydeveloped wireless CROS instrumentsthat did away with the need to use wiresand cords to connect each side.

In 1970, Al Dunlavy, a hearing aiddispenser in Manhattan wrote an articlefor Audecibel, a publication of theNational Hearing Aid Society,1 with thetitle, “CROS: The New Miracle Worker.”Why would he call CROS, of all things,a miracle? And was it really? This articledeals with the specific and uniqueapplication of the CROS aid that hewrote of that was never originallyintended, but that eventually became itsmost significant form of usage, such as,a solution to the problem of feedback.

Until the advent of CROS fittings,problems with feedback dogged theindustry. Today open canal fittings areroutine, seldom requiring a secondthought to feedback issues. Feedbackcancellation algorithms make bilateralhigh frequency fittings a walk in thepark. One can literally grab a couple ofunoccluded ear buds from off the shelfand fit without ever giving a thought to

the issues faced years ago.

THE HARVARD REPORT ONHEARING AIDSTo get a fuller appreciation of the impactof CROS on the practices of the day, wecan go all the way back to 1947, aboutthe time audiology began. That year afamous research monograph on hearingaids was published, referred to as theHarvard Report.2 At the time thePsychoAcoustics Laboratory at HarvardUniversity was the single most influentialresearch center in the United States onmatters auditory and acoustic. The reportrecommended that a flat or 6 dB peroctave slope frequency response wasadequate for the majority of patients whoneeded a hearing aid, and it severelycriticized other methods of fitting,implying they were a waste of time.

At about the time of the Harvard Report,Raymond Carhart, generally consideredthe “father of audiology” in NorthAmerica, published procedures forselecting the appropriate hearing aid.3–5

Although criticized by the HarvardReport, this (comparative) method gainedmuch ascendancy in the universityclinics. Aids were pre-selected from clinicstock for inclusion according to the bestjudgment and preferences of theprofessional. Only body aids wereavailable then, and during the evaluation,the instrument’s case was placed on a(baffle) board alongside the patient. Thepatient was tested in a sound field,usually but not always, with stock molds,

How Open Canal Amplification Was Discovered

By James R Curran, MS

About the AuthorJames R. Curran is a consultantwith Starkey Hearing Technologies


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and often, but not always, withoutventing. Feedback problems were not abig issue unless the loss was substantial,for the aid’s microphone and receiverwere at a good distance from each other.Importantly, conventional wisdom at thattime held that on average, aided wordrecognition scores were not expected toexceed the unaided score, which servedas a target. The best performing aids werethose that provided aided scoresapproximating the unaided scoreobtained under circumaural earphones,for it was expected by comparison, thatthe degraded signals provided by thehearing aid would result in lower scores.6

The Harvard Report recommendations ledthe early audiology world astray foryears. Fitting hearing aids with a flatresponse or a 6 dB per octave responseon patients having other than flat ormoderately sloping thresholdconfigurations led to many dissatisfied,poorly performing patients. And easilyaccessible information regarding theeffect of the earmold on the amplifiedresponse was, for all intents andpurposes, nearly nonexistent.

Fitting problems multiplied when thefirst BTE and eyeglass aids reached themarket in the early 1950s. The twotransducers were positioned much closerto each other in head worn instruments,and manufacturers had a difficult timekeeping receiver vibrations from spillingover into the microphone. Further, widerbandwidth was possible with head wornaids, and this increased the probability ofacoustic feedback problems. The resultwas a high incidence of internal andexternal feedback issues. One could usefull shell earmolds having minimal or noventing in order to eliminate externalfeedback, but that exacerbated theocclusion effect for many patients.Professionals were fitting rather

unrefined aids with little or nounderstanding of earmold acoustics topatients who, then as now, invariablypresented with losses having a highfrequency component. The usualoutcome was frustration on the part ofthe professional, and dissatisfaction onthe part of the patient.

It is no wonder that hearing aid fittingbecame one of the least desirable aspectsof audiology during those years. Few ifany students opted for making hearingaids the major focus of their studies; infact it was regarded as somewhat déclasséif one did, and pity the brave instructorwho taught amplification, for reliablefacts were few and far between.

THE BEGINNING OF WISDOMFully five years prior to Dunlavy’s articlementioned above, Earl Harford, aprofessor at Northwestern University,began to document the advantage of theCROS concept and reported it to thescientific community.7 He and hiscolleagues published a series of studiesin the professional journals exploring itspotential and its benefits.8–12 Almostimmediately professionals recognizedthat CROS was not just a solution forunilateral hearing loss, but rather,because the microphone and receiverwere on separate sides, it was possible toprovide high gain, high frequencyamplification without encountering feedbackfor patients with high frequency losses. Sincenearly all fittings in those days weremonaural anyway, every patient whopresented with a bilateral (or unilateral)sloping high frequency loss was acandidate, and was assured of a nearlyperfect fitting in at least one ear using anopen mold. It was finally possible todeliver the satisfaction that the hearingaid advertisements promised.

In one fell swoop this unique CROS

application dealt with a number ofissues. Papers began to appear in theaudiological literature showing that aideddiscrimination scores actually didimprove markedly with open canalamplification compared to scores thathad been obtained under earphones orwith occluded earmolds.13–16 This was asurprise to many for although it wasknown that test scores varied as testconditions changed (talker, level,transducers, test stimuli, etc,) for somereason this understanding had neverfully registered in the case of hearing aidfittings. The improvement in scoresresulted from, 1) the high frequenciesreceiving markedly greater amplificationthan had been possible heretofore, 2) thehigh frequency amplification bandwidthbeing significantly wider than waspreviously achievable, 3) the occlusioneffect being virtually eliminated, and, 4)as a bonus, upward spread of maskingeffects being reduced due to the absenceof amplification in the low frequencies.These results set in motion countlessresearch studies over the years dealingwith the benefits and usefulness of highfrequency amplification and itscontribution to word recognition in bothchildren and adults, and produced manystudies dealing with the effect of theearmold/coupling on the frequencyresponse.

ACHIEVING MIRACLESIt is instructive to visit the steps ofhearing aid dispensers who were fittingCROS hearing aids, (prior to theintroduction of wireless CROS). First, thepatient had to be wearing zyl (specialplastic) eyeglasses, or the patient waspersuaded to purchase a pair. If he/shedid not wear glasses, they were asked toget a pair with plain glass lenses. Theframes had to have so-called “standardhinges” because the graduated templeterminations furnished with the eyeglass

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hearing aids were only available with thistype of hinge. Then a small circularmotor-tool saw blade was used to cut atrench across the back of the plasticframe, from hinge to hinge. A very thinplastic cable containing two or threeextremely fine wires was placed in thetrench and covered over with a plasticsealant. After it had dried, the insidecovers of both hearing aid temples wereremoved, and the fine wires weresoldered to the microphone on one sideand to the circuitry and receiver on theother. The temple covers were thenreglued or screwed back into place. Theeyeglass temples and frame were heated,bent and adjusted so that the patient wascomfortable with the glasses. A shaved-down pipe cleaner was inserted into alength of earmold tubing and bent to theright shape for secure placement in theear canal. The tubing was heated with ablower until it set. If needed, the hearingaid’s response could be manipulatedsomewhat by changing the depth of thetubing in the ear canal or by using tubingwith different exterior dimensions.

Why would professionals go throughsuch a complicated, lengthy andconvoluted process? The answer is thatthey never had so many grinning,enthusiastic, happy customers. Hand-holding just about disappeared if thepatients were fitted with CROS; most oldand new customers experienced wearingsuccess right out of the box. Even withall the rigamarole that attended CROSinstallation and fitting, countlessprofessionals routinely chose torecommend and to fit them. To them,

fittings without feedback problems wereindeed miracles. In the early 1970s, therecords show that in some years CROSfittings accounted for nearly 20% of allhead worn aids. By 1974, Harford andDodds11 suggested that CROS fittingshad probably reached close to 40% of allrecommendations in University audio-logy clinics.

The CROS concept and the children thatit spawned (IROS, BiCROS, Hi-CROS,etc) became a somewhat neglected fittingoption in ensuing years, as custom ITEaids grew in importance. The wonderfulsolution to feedback issues that CROSprovided was essentially forgotten, andCROS was seen again solely as anapplication suitable for fitting unilaterallosses. The advantage of an open canalfitting however, never disappeared, andwhen it appeared feasible again as a resultof modern feedback control methods,the miracle happened all over again.

During an audiology convention a fewyears ago, a speaker remarked to theaudience that the open canal technologyof today shouldn’t be confused with theold CROS and IROS fittings of yearsago. The speaker was in error, of course,for it’s the same idea. Today’sprofessionals are standing on theshoulders of some very tough andcommitted professionals who developedthe original technique, changed a lot ofwidely held assumptions, and broughtto the fore many of the importantunderstandings we hold today aboutproviding acceptable amplification forhigh frequency losses.

REFERENCES1. Dunlavy AR CROS: The new miracle worker.

Audecibel 1970;141–8.2. Davis H, Stevens SS, Nichols RH, et al. Hearing

aids: An experimental study of design objectives. Cambridge: Harvard University Press; 1947.

3. Carhart R. Selection of hearing aids. Arch Otolaryng 1946;44:1–18.

4. Carhart, R. Tests for the selection of hearing aids.Laryngoscope 1946;56:780–94.

5. Carhart R. Hearing aid selection by university clinics, J Speech Hearing Dis 1950;15:106–13.

6. Hirsh LJ. The measurement of hearing. New York: McGraw-Hill; 1952.

7. Harford E and Barry J. A rehabilitative approachto the problem of unilateral hearing impairment:the contralateral routing of signals (CROS). J Speech Hearing Dis 1965;30:121–38.

8. Harford E. Bilateral CROS. Two-sided hearing with one hearing aid. Arch Otolaryngol 1966;84:426–32.

9. Harford E. Innovations in the use of the modernhearing aid. Internat Audiol 1967;6:311–14.

10. Harford D. Recent development in the use of ear–level hearing aids. Maico Audiological Series1968;5(3):10–13.

11. Harford E and Dodds E. Versions of CROS hearing aids. Arch Otolaryngol 1974;100:50–57.

12. Dodds E and Harford E. Modified earpieces andCROS for high frequency hearing loss. J SpeechHearing Dis 1968;11:204–18.

13. McClellan, M. Aided speech discrimination scores in noise with vented and unvented earmolds. J Aud Res 1967;13:93–99.

14. Green D and Ross M. The effect of a conventional versus a nonoccluding (CROS type) earmold upon the frequency response of a hearing aid. J Speech Hearing Res 1968;11:638–47.

15. Hodgson W and Murdock C. Effect of the earmold on speech intelligibility in hearing aiduse. J Speech Hearing Res 1970;13:290–97.

16. Jetty A and Rintelmann W. Acoustic coupler effects on speech audiometer scores using a CROS hearing aid. J Speech Hearing Res 1970;13:101–14.


Reprinted with kind permission from Starkey HearingTechnologies.


| RESEARCH AND DEVELOPMENT FOCUS

Diabetes Mellitus (DM) is one of thefastest growing chronic diseases of

our era. Recent studies suggest thatsensorineural hearing loss is moreprevalent in diabetic patients than inpeople without the condition. The aim ofthis article is to review the existingliterature on the relationship betweenhearing loss and diabetes. Data wasobtained by literature search using theMEDLINE, EMBASE and PubMeddatabases.

Diabetes mellitus is a group of metabolicdisorders characterized by an elevatedblood sugar and abnormalities in insulinsecretion and action.1 This group ofdisorders disrupts the metabolism ofprotein fats and carbohydrates renderingthe body unable to utilize these nutrients.The resultant hyperglycemia can lead todysfunction of several organs. Damage isnoted in the nervous system, eyes,kidneys, heart and blood vessels.2 In the

non-diabetic individual blood glucoselevels are controlled by insulin, ahormone produced by the beta-cells ofthe pancreas. When glucose levels rise inthe blood stream (for example after ameal) insulin is released to normalizeglucose levels. In the diabetic patientinsulin production is either severelydeficient in the pancreas or the pancreasis producing insulin but the body isunable to utilize it.3

There are two major types of diabetes.DM type I results from autoimmunedestruction of the beta-cells of thepancreas. Ten percent of all diabetics inthe United States are typically diagnosedin childhood or adolescence. Patientswith DM I are insulin dependent andrequire close monitoring of blood sugarlevels to ensure blood glucose iscontrolled throughout the day. This typeof diabetes was formerly known asinsulin-dependent diabetes mellitus

(IDDM).4 DM type II is characterized byresistance such as a lack of response toinsulin by the cells of the body (mainlyfat and muscle cells), along withincreased insulin production by the liverto overcome this resistance. It accountsfor 90% of all cases of diabetes. It istypically diagnosed in adulthood and isclosely associated with obesity. DM II ismanaged by diet, weight management,oral medications and/or insulin.5 Type IIdiabetes was formerly known as non-insulin-dependent diabetes mellitus(NIDDM), but this term has beenabandoned since most of the patientswith DM II will require insulintreatment at some point in the course oftheir condition.6 The prevalence ofdiabetes among adults within the 20–79year range was estimated to be 6.4% in2010, affecting 285 million peopleworldwide. The prevalence is expectedto rise to 7.7% and 439 million adultsby 2030.7

The Link between Diabetes Mellitus and Sensorineural Hearing Loss: A Summary of the Evidence

By Eirini Mihanatzidou, MA(Hons), M.Aud, Aud(C), Reg. CASLPO, and Rhonda Kerlew, RN, BScN, MBACorrespondence: Hearing Solutions, 620 Wilson Avenue, Suite 200, Toronto, ON, M3K 1Z3, T: (416) 231-3003, F: (416) 623-1245, www.hearingsolutions.ca

About the AuthorsEirini Mihanatzidou (far left) is an audiologist with Hearing Solutions,Toronto, Ontario.

Rhonda Kerlew is director of business development with Hearing Solutions,Toronto, Ontario.

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Both types of diabetes are associated witha number of chronic complications andco-morbidities. The most prevalent andwell known complications includeretinopathy, nephropathy, and peripheralneuropathy.8 Each of these complicationscarries its own set of losses anddysfunction such as blindness, kidneyfailure, and peripheral vascular diseaserequiring amputation.9 Another, less wellknown complication of diabetes ishearing impairment. Accumulatingevidence suggests that there is a higherprevalence of hearing loss in the diabeticversus the non-diabetic population.10–12

The hearing loss is bilateral,sensorineural, symmetrical, and tends toaffect the high frequencies more than thelow/mid ones.13,14

More specifically, Dalton et al. found that59% of diabetic subjects had a hearingloss as opposed to 44% of non-diabeticsubjects.15 The association betweendiabetes and hearing loss was significantwhen results were analyzed excludingsubjects with non age-related hearingloss. In a study conducted by Bainbridgeet al. 68% of patients with diabetes werefound to have some high-frequencyhearing loss compared to 31% ofsubjects without diabetes.16 Theprevalence of low/mid frequency hearingloss was 28% in the diabetic patients asopposed to 9% in the non-diabeticgroup. The association between diabetesand hearing loss remained even aftercontrolling for age, race, sex, povertylevel, history of noise exposure, ototoxicmedication use, and smoking status. Thestudy by Mitchel et al. is in line with theabove findings.17 More specifically,hearing loss was found in 50% ofdiabetic patients compared to 38% of thenon-diabetic subjects after adjusting formultiple risk factors. Furthermore, astudy by Uchida et al. found thatdiabetes may affect the high-frequencies

more strongly in the age bracket of 40–64 years of age than at age 65 andabove.18 Finally, a study conducted in2009 by Cheng et al. revealed that theprevalence of hearing loss amongstdiabetics has remained high over thedecades when compared to non-diabeticpersons.19 More specifically, the authorscompared the two cross-sectionalNational Health and NutritionExamination Surveys of 1971-1973 and1999-2004 (NHANES I and NHANESII). They discovered that from 1971 to2004 in adults without diabetes aged 25–69, the unadjusted prevalence of hearingloss decreased by 9% whereas in thediabetic population there was nosignificant change.

With regards to the risk factors forhearing impairment in the diabeticpopulation, evidence is conflicting. Anumber of studies have shown thathearing loss is correlated with glycaemiccontrol (i.e. with the blood glucose levels)and duration of disease.20–22 Morespecifically, Okhovat et al. compared thehearing thresholds of 100 patients withDM I aged 5–18 years.23 They found that21% of them had a hearing impairmentand that the hearing thresholds werepositively correlated with poor metaboliccontrol (defined as an annual HbA1C ofmore than 7.5%). Furthermore,thresholds were significantly higher inpatients with a history of diabetes of morethan five years. Additionally, two studiesby Lerman-Garber et al. and Konrad-Martin et al. reported a positiveassociation between poor glycaemiccontrol and impaired auditory brainstemresponses in DM II patients.24,25 Pudar etal. examined the effects of peripheralneuropathy and retinopathy on hearingimpairment in 50 patients with DM I andfound that the average sensorineuralhearing loss was increased by 73% in thepresence of neuropathy, and by 50% in

the presence of retinopathy.26 Bainbridgeet al. found a strong correlation betweenneuropathy, duration of disease and high-frequency hearing impairment in 536diabetic patients, whereas Dabrowski etal. found higher mid frequencythresholds in 31 patients with DM I andretinopathy.27,28 However, both of thesestudies, as well as a third study by Asmaet al., failed to find a correlation betweenglucose levels and hearing loss.29

Recent studies suggest that diabetes mayalso increase the susceptibility to noise-induced hearing loss and suddenidiopathic sensorineural hearing loss(SISNHL). More specifically, Wu et al.and more recently Fujita et al. reportedon an animal study in which diabetic ratshad a significantly impaired recoveryfrom a temporary noise-inducedthreshold shift.30,31 Furthermore, Jang etal. found that the hearing thresholds at 4kHz in 2,612 automobile factory workerswere significantly worse in subjects withimpaired fasting glucose and diabetesthan in non-diabetic subjects.32 Aimoniet al. studied the prevalence of diabetesin patients with sudden idiopathicsensorineural hearing loss and found thatit was almost doubled when comparedwith the normal hearing subject group.33

It has been suggested that diabetes canmediate SISNHL through cerebralmicroangiopathy and changes in bloodviscosity.34,35

The exact mechanism involved in thepathogenesis of hearing loss in diabeticpatients remains unknown. A number ofhistopathological studies conducted inhumans found thickening of the capillarywalls of the stria vacsularis, the basilarmembrane and the endolymphatic sac,atherosclerotic narrowing of the internalauditory artery, atrophy of the striavascularis, loss of outer hair cellsespecially in the lower basal cochlear


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turn, spiral ganglion neural atrophy, andVIII cranial nerve demyelination.36–39

In all, hearing impairment is one of theless well known complications of diabetes.More research is needed to delineateassociated risk factors and mediators in itspathogenesis. Untreated hearing loss cannegatively impact the social and emotionalwellbeing of individuals.40–43 Theproportion of hearing impairment in thediabetic population in comparison withthe non-diabetic population is high. Inlight of its high prevalence and itsdetrimental psychosocial effects, healthcare providers, primary care physiciansand endocrinologists should considerreferring all diabetic patients for a hearingtest. Audiometry should be a routineevaluation in the annual test battery of alldiabetic patients.

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3. Anderoli TE, Carpenter CCJ, Griggs RC, Benjamin IJ, eds. Cecil Essentials of Medicine. 7th ed. Philadelphia: Elsevier Saunders, 2007.

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25. Lerman-Garber I, Cuevas-Ramos D, Valdes S, etal. Sensorineural Hearing Loss – A common finding in early-onset type 2 diabetes mellitus, Endocr Pract 2012;18(4):549–57.

26. Pudar G, Vlaski L, Filipovic D, Tanackov I. Corellation of hearing function findings in regards to other, subsequent complication of diabetes mellitus type 1. Med Pregl 2009;62(11–12):517–21.

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organ in Type 1 diabetes mellitus. Endokrynol Pol 2011;62(2):138–44.

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41. Kaland M, Salvatore K. The psychology of hearing loss. The ASHA Leader. 2002;7(5):4–5:14–15.

42. Boi R, Racca L, Cavallero A, et al.. Hearing loss and depressive symptoms in elderly patients. Geriatr Gerontol Int 2012 Jul;12(3):440–5.

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