Hearing Aids

Hearing Aids

RATING: (5 of 5 ears)
AUTHOR: Harvey Dillon
PUBLISHER: Boomerang Press, distributed by Thieme
ISBN: 1-58890-052-5
COST: $59.00

REVIEWER: Alison M. Grimes, MA, Director of Audiology, Providence Speech and Hearing Center, Orange, CA

SYNOPSIS: This text is a comprehensive look at hearing aids, their selection and fitting, and the counseling and assessment of outcomes that accompanies their successful use, from the basic to the advanced concepts. The book comprises 16 chapters, from hearing aid components and signal processing through selection, counseling, assessing outcomes and special considerations for children. Liberal use of well-designed figures, and peppered with humor, this is a very readable text. Complex concepts are presented in a user-friendly and understandable fashion, without compromising detail or precision. Not only are hearing aids, assessment and fitting considered, but there is considerable discussion of basic psychoacoustic factors such as binaural hearing, masking, loudness growth, etc., as well as psychological aspects of impaired hearing, This is an exhaustive and in-depth look of virtually all aspects of hearing aids themselves, and the professional issues surrounding their successful fitting.

REVIEW: Setting the stage for the topic of the text is Chapter 1, "Introductory Concepts," which looks at the problems faced by people with hearing impairment: not only decreased audibility, but decreased frequency and temporal resolution and decreased dynamic range. Acoustics, types of hearing aids, and a historical perspective on hearing aids takes the reader from ear trumpets to digital hearing aids.

Hearing aid components are thoroughly analyzed in Chapter 2, including not only components of the aid itself, but such issues as remote controls, bone conduction receivers and batteries.

Ditigal vs analog, FM and induction principles are laid out in chapter 3, with additional information on classroom sound-field amplification and ALDs. A little humor in chapter 3 typifies that seen throughout the book—"Why does the hearing aid wearer need to change programs (multiple memories)? It's not as if a drama can be heard on one program and a comedy on another!"

Electroacoustic measurements and probe-microphone measurements are examined in chapter 4, including a significant list of good practical tips to ensure accurate probe-microphone measures.

An entire chapter on compression is a well-written and complete discussion, including a comparison of compression types, and rationale for choosing one compression scheme vs another. Figure 6.3 is just an example of how clear and simple figures complement this text, with a side-by-side comparison of linear, slow, medium and fast attack/release compression circuits.

Directional microphones, frequency transposition and feedback reduction options are covered in Chapter 7.

Chapters 8-13 form a complete look at candicacy, prescribing hearing aid performance, seelection and adjusting, problem-solving and fine-tuning, counseling and assessing outcomes. These chapters are distinguished not only by fine technical information, but practical, real-world suggestions and considerations for successful fits (e.g., "Twelve steps for selecting and adjusting programmable hearing aids" amd "Adjusting to new experiences with sound and hearing aids."

Chapter 9 takes a gentle jab at hearing aid researchers and the plethora of prescriptive fitting formulas: "Making up a procedure is easier, more fun and less discouraging than evaluating how well it works!"

Chapters 12 and 13 are particularly patient-centered, and consider such issues as communication training, involving families and friends, ongoing support and counseling, and the impact of hearing aids on general health and quality of life.

Chapters 14 and 15 look at binaural hearing, bilateral hearing aids and special issues for infants and children, including such topics as sensory deprivation in hearing impaired children, a step-by-step "how-to" obtain and apply, RECD measures in children, and a look at some pediatric outcomes measures. Implanted and semi-implanted hearing aids complete this text, with a discussion of the BAHA and an introduction to middle-ear implants.

Although not a text for cochlear implants, this book carefully documents cochlear implant candidacy. Perhaps the first line sums up the scope of the problem: "Hearing aids partially overcome the deficits associated with a hearing loss." The reader of this text who applies the knowledge contained within will certainly be able to maximize their ability to overcome these deficits to the benefit of their patients.

CRITIQUE: Harvey Dillon is certainly one of the world's best hearing aid experts to put together a text such as this. From the basic (earmold types and tubing effects) to the complex (digital signal processing, compression schemes) to the human (why teenagers reject their hearing aids) to the practical (why cerumen affects probe microphone measures), this book covers it all. This would be a valuable text for a graduate-level hearing aid seminar, as well as a clinic reference text for practicing audiologists. Additionally, portions of this book could be easily integrated into undergraduate Auditory Rehabilitation courses.