Hearing Instrument Technology for the Hearing Health Care Professional

Hearing Instrument Technology for the Hearing Health Care Professional

RATING: (5 out of 5 ears)
AUTHORS: Andi Vonlanthen and Horst Arndt
PUBLISHER: Thomson Delmar Learning, Clifton Park, NY
ISBN: 1-4180-1491-5
COST: $56.95

REVIEWER: Steven D. Sederholm, AuD, Private Practice, Boynton Beach, FL

SYNOPSIS: The second edition of this book, Hearing Instrument Technology for the Hearing Health Care Professional, was published just six years ago, but due to the rapid advances in hearing device technology, it became necessary to introduce this latest edition. It appears the evolution of digital sound processing technology is primarily responsible for many of the additions and revisions of this latest version. Essentially every chapter has been enhanced with information concerning the evolution of digital technology. However, additional discussions also covered such topics as cell phone interference, data transmission techniques, shell-making processes, and implanted devices.

Hearing Instrument Technology for the Hearing Health Care Professional: This book was primarily designed as an educational text, but is also appropriate for use by seasoned clinicians or hearing instrument engineers. The authors made every effort to provide technical explanations only when necessary, keeping mathematical formulas and calculations to a minimum. It would be impossible to thoroughly describe the content of all 16 chapters in this review, but it is imperative to mention several key sections of this very comprehensive text.

Chapter 2, titled Hearing Instrument Components, includes an impressive description of directional microphone and multiple microphone technology. The chapter contains an interesting historical perspective of several key hearing aid components, including the microphone. Chapter 5 discusses digital signal processing that allows the reader to gain a thorough understanding of the advances and improvements afforded by this new technology. Chapter 7 includes a considerable amount of information concerning FM technology and the clinical measurement of these systems. It was most interesting to read the discussion on Hearing Instrument Troubleshooting in Chapter 8, information not often covered in many hearing aid texts. New advancements in the production of hearing aids include laser scanning and shell fabrication, which is covered thoroughly in Chapter 10. There is a good deal of information on hearing aid verification techniques in Chapter 11. Classic prescriptive formulas were discussed (as well as the more recent introduction of the DSL and NAL-NL1 formulas). Much attention was paid to loudness scaling techniques, as well as "questionnaire-type" outcome scales including the APHAB, COSI, and HHIE/A.

Psychoacoustics and the anatomy/physiology of the hearing mechanism were briefly discussed in Chapter 12-but it should provide the reader with a surprisingly thorough understanding of these subject areas. Of note is the discussion on the relationship between psychoacoustic correlates to physiological processes. In addition, the authors attempt here to explain how anatomy, physiology, and psychoacoustics are related with respect to the impaired ear and how this affects our ability to communicate; again, a subject not covered in many other hearing aid texts.

It is commonly known that digital cell phones have in the past caused interference with the use of hearing aids. This topic is covered in detail in Chapter 13, Interference in a Digital World. Recent advancements in hearing instrument immunity to cell phones are briefly discussed, and the 2003 regulatory ruling requiring manufacturers to offer two cell phone models that comply with the "U3" rating is also mentioned.
Data Transmission is covered in Chapter 14. After a brief discussion of binary mathematics is presented, the reader is able to better understand current and upcoming technological innovations, including data compression and the MP3 format, Bluetooth transmission, and wireless fidelity (WI-FI). Finally, a chapter is dedicated to implanted devices, including the BAHA system, middle ear implantation, and auditory brainstem and cochlear implantation.

Review Questions appear at the end of each chapter, as the authors wished to improve upon the educational nature of the text.

CRITIQUE: Hearing Instrument Technology for the Hearing Health Care Professional is an extremely comprehensive work, seemingly covering every imaginable area of hearing instrument and assistive technology. It is appropriately suited for the graduate student, the clinical researcher as well as the acoustic engineer. The material is designed in an organized fashion, making very complex subjects an "easy read." The photographs, charts, and figures supplement the text quite effectively, facilitating a thorough understanding of the material.

It is surprising to this reviewer that more information about the use of real ear probe tube measurements was not contained in the text. Perhaps this is a "sign of the times," as it seems this verification tool has not recently enjoyed the popularity it did 20 years ago. Implications for future revisions would include the discussion of the post-auricular non-occluding (open) hearing instrument, a product which has generated tremendous growth over the past year or two.

Overall, this text will serve as a valuable tool for all, even the most experienced practitioner. It is a "must have" for every dispensing audiologist's personal library.