By Joel M. Mynders, BC-HIS
Author’s Note: This article was originally written as one cohesive paper intended to provide the basics on hearing aid selection. While it could have taken the form of a book chapter or a monograph, it was decided to publish the article as a three-part series due to its length. It is hoped that such a presentation will facilitate the incorporation of some of the ideas by hearing care practices throughout the country.
The following is neither an exhaustive list of all the possible approaches and tests that can be used during the hearing aid selection process, nor does it consider the plethora of devices that exist apart from hearing aids (eg, assistive devices, cochlear implants, and middle ear implants). The truth is that the methods for working with hearing instruments and hearing-impaired individuals rely largely on a commitment to asking the right questions, caring for the patient, and an imagination that draws on solid audiological knowledge. There is not likely to be only one appropriate approach for any given patient. Likewise, any strict formula for hearing aid selection without the questioning, caring, and imagination of the practitioner would be probably be too restrictive for real-world dispensing.
Only time and experience will tell which of these (or other) methods will work for you and your patients. And, without question, the methodology will change as new technology becomes available and new information emerges relative to amplification and the people-machine interface that dispensing professionals strive to bridge in their practices each day. The following is hoped to provide guidance and some “road signs” during the hearing aid selection process.
Link to Part 2: It’s in the Numbers: Selection by Measurement, Circuitry, Components, and Expert Fitting Techniques
The Basics of Hearing Aid Selection
Hearing aid selection is a complex part of hearing rehabilitation. The selection process follows the clinician’s assessment of a patient’s candidacy for amplification, and precedes the hearing aid fitting, verification, and validation processes.
When the decision in favor of treating the particular case in point is made, the clinician is confronted with multiple decisions to customize the client’s treatment with amplification. The clinical challenge is to weigh the many factors in the selection process to achieve an optimum fitting. It is a fact that there is not just one possible hearing aid fitting per patient. Therefore, patients and clinicians usually have many choices in the selection of treatment. Essentially, the patient’s goals, the clinician’s assessments, and all of the potential fittings somehow must merge during the fitting process to arrive at the most successful rehabilitation outcome. It should be obvious that many experienced professionals have developed their own way for accomplishing this objective, and these methods may deviate substantially from the methods presented here.
For the purpose of this article, the Hearing Aid Selection Process will be divided into three parts:
Part 1: Selection by the Physical Factors of Cosmetic, Anatomical and Dexterity Issues, and Selection by Needs Assessment;
Part 2: Selection by Measurement, Circuitry and Components, and Expert Fitting Techniques, and
Part 3: Selection by Perception and Paired Comparisons.
In everyday practice, the above dispensing elements may be used formally or informally. In the development over time of selection protocols, one or two of these categories may have dominated. For example, selection by measurement (covered in Part 2) has been historically favored by audiologists, while selection by perception (covered in Part 3) has been historically favored by hearing instrument specialists. It’s probably fair to say that the situation at present—by all dispensing professionals—favors usage of most of these three parts in order to yield the best outcomes for the applied amplification of hearing-impaired patients.
From a purely pragmatic point of view, how do you as a hearing care professional decide what hearing aid to fit a patient with? An everyday three-part categorization may provide a practical framework for the selection process used in most practices:
1. Clinical Considerations
a. Type of hearing loss (sensorineural, conductive, or mixed);
b. Degree of hearing loss (mild, moderate, severe, or profound);
c. Sensitivity to sounds, tolerance/recruitment problems, and dynamic range;
d. Psychological attitude toward correction (eg, motivation and the primary motivator);
e. Contraindications for correction.
2. Physical Conditions of the Patient
a. Shape and size of ears and ear canal;
b. Manual dexterity and finger sensitivity;
c. Mental acuity.
3. Patient Wishes/Preferences
b. Needs assessment;
c. Appropriate circuit choices (digital, programmable, etc);
d. Appropriate controls (eg, AGC, VC, remote control, directional microphones, etc).
The following sections provide an abbreviated description of the above subheadings. The inclusion of a larger resources section is provided at the end of this article for those interested in further detailed reading about this rich subject in the hearing aid literature.
Selection by Physical and Cosmetic Factors
Even before electronic devices were available, the hearing-impaired population was very concerned about the appearance of “hearing aids.” The concern is based on the perceived message that hearing aids are a visible indicator of declining faculties. This change potentially involves the way people think about the patient and what kind of message that patient is broadcasting to other people. This message, in reality, relies on human interaction and involves that most powerful commodity: self-perception or self-actualization.
Throughout history, all perceived handicaps have been a potential source of isolation. Current attitudes and laws about hearing handicaps are changing these past responses, but the prospect of rejection by society is still a reality (perceived or otherwise) for those considering amplification. In a 1978 study by Surr, Schuchman & Montgomery1 entitled “Factors Influencing Use of Hearing Aids,” the authors found that 1 in 4 (26%) potential hearing aid users felt that others would view them as “older” if people saw them using hearing aids. There are not a large number of articles on this theme, but all experienced dispensing professionals are certainly aware of the need to work on patients’ perceptions about the cosmetic aspects of hearing aids. To minimize this part of the hearing aid selection process is simply not good clinical management. For a successful fitting, the patient first has to wear the hearing aids in public with confidence.
Figure 1. A variety of hearing instruments have been used over the years, even including a tin kitchen funnel (lower right).
Figure 1 shows several types of non-electrical hearing devices from the history of our profession. Many are characterized by a need to hide the devices. Over the majority of the past 90 years—since electrical hearing aids became an option—the greatest efforts in design have continued to relate to cosmetic, not acoustic, concerns. In fact, although acoustic concerns were certainly a consideration in designing hearing aids throughout the decades, it wasn’t until the 1980s—when hearing aids became widely available in ITE/ITC configurations—that we were able to approach amplification with anything that might resemble an “invisible” or truly “discreet” option.
Today, most patients have numerous cosmetic options from which to choose. There are a few groups of hearing losses that cannot use certain cosmetic options due to acoustic performance limitations.
The dispensing professional is confronted with a conundrum when assessing the physical/cosmetic factor. Trying to provide the cosmetic choice of the patient is important. But, should the size of the aid be the primary factor in selection of the hearing aid style? Remember, patient motivation is highly connected to the time the hearing instrument is used by the patient and effective hearing correction.
Figure 2. A general guideline for cosmetic options versus hearing loss types/configurations as provided by Gail Gudmundsen, MA. It should be noted that these are general recommendations; different hearing aid models/styles vary widely in gain, dynamic range, fitting flexibility, etc, so consulting manufacturers’ specifications is always advised. A similar version of this chart by Gudmundsen appears in Tobin’s book, Practical Hearing Aid Selection and Fitting.2
The cross-referencing of cosmetic options and acoustic performance has been concisely presented by Gail Gudmundsen (Figure 2).2 Current practice and expanded model and performance options have created a wide range of fitting possibilities for patients.
Selection by Physiological, Anatomical, and Dexterity Factors
The anatomical parameter of the hearing aid selection process includes otoscopy and a general examination of the ear canal and external ear. The physical status of the entire external ear and eardrum is important in the hearing aid selection process. It should be noted that all external ears differ as much as fingerprints differ from person to person. The right and left ear of the same individual can differ substantially, as well.
Wormald & Browning’s 1996 book, Otoscopy: A Structured Approach,3 contains some of the best photos and graphs for hearing aid clinicians to hone their observation skills in otoscopy. Otoscopy in the hearing aid selection process reveals diseased or non-diseased ears, the condition (or even absence) of the eardrum, and the size, shape, and configurations of the canal and concha. All of these observations can affect the selection process.
Deformed or malformed ears will require an altered selection of hearing aids, since these problems will affect retention and feedback during hearing aid usage. An extreme condition, such as the absence of the pinna, will alter the selection process by the dispensing professional since there may be no concha, canal, or both.
Another anatomical situation that can occur is the presence of a surgically treated ear that has a large irregular ear canal that may open wider once past the canal opening. Findings of this anatomical situation will require careful selection to avoid fitting complications. In recent years, completely in the canal (CIC) style hearing aids emphasize the need for observing canal configurations. Fortunately for dispensing professionals, a book on this subject that is extremely useful is Bopanna Ballachanda’s 1995 text, The Human Ear Canal.4
The canal inspection may reveal tenderness, abnormalities (eg, stenosis), surgical scars, dermatological conditions, fat or thin canals, prolapsed canals, unusual bends upward or at peculiar angles, etc. These visual findings may suggest contraindications for such choices as CIC type instruments and other special selections by the clinician.
Based upon the otoscopic and physical examination of the external ear canal and eardrum, Table 1 is a general list of otoscopic and anatomical situations with possible solutions/options for each. This list does not attempt to detail all possible situations and selection options that may arise in a dispensing practice.
|Situation||Possible Selection Option(s)|
|Lack of pinna||Bone conduction fitting|
|Lack of canal||Bone conduction fitting|
|Draining ear (treated)||Multiple options/Aerated canal|
|Prolapsed canal||Short canal with extended tubing
BTE and some custom styles
|Severe dermatitis (treated)||Hypoallergenic shell or mold|
|Close-cropped pinnas||ITE, ITC or CIC style aid|
|Sharp (eg, 45°) bend in canal||Short canal aid or ITC style|
|Large bone or tissue movement||Soft canal or mold, or custom with jaw action aid. Use of canal lock extension|
|Tenderness in canal wall||Soft material for mold or shell;
Use of Otofirm or Otosilk.
|Tenderness in concha||Soft mold BTE aid|
|Surgically treated canals||Soft mold/short canal. Tragus
mold configuration BTE
|Stenosis in canal||Mold or aid to be fitted before
stenotic area. Shorter canal aid
The question of dexterity and mobility are additional physical factors in selecting hearing aids. These two factors can affect younger, as well as older, individuals. The insertion, removal, and operation of various hearing aid styles must be evaluated carefully by the clinician. Stroke patients, in particular, may have inhibited manual capabilities. Some patients may have reduced sensitivity of touch in their fingertips, and medications can also affect the above. Likewise, hand size and the presence of tremors (eg, Parkinson disease) are in this group of factors in selecting an appropriate hearing aid for the individual.
A very easy protocol to incorporate into the selection process is to have the patient operate a sample hearing aid. In this way, one can observe in advance their use of a remote control, volume control, etc, prior to the hearing aid being selected. The process should also include the patient’s use of other controls and battery insertion and removal. This observation takes little time, and it can remove some disappointment and embarrassment for the patient at the actual fitting/delivery session. In real life, patients usually know what they can and cannot handle when it comes to dexterity and mobility issues; however, certain patients will either have their heart set on a particular style, or be reluctant to inform the clinician that they have dexterity/mobility limitations. It’s the clinicians’ job to find this out before ordering the hearing aids.
Circuit Selection and Needs Assessment:
A Return to Patient-Driven Care
In the beginning of electronic hearing aids, there were only body aids with linear circuits. Circuit choice was not an option. The patients elected to use amplification or they didn’t. The present situation has literally hundreds of hearing aid product lines, models, and styles from which to choose. A simplified breakdown of current circuit options might be as follows:
- Analog linear (traditional linear aid)
- Standard Compression (automatic gain control at input/output )
- Advanced Compression (automatic signal processing, eg, BILL, TILL)
- Advanced Non-Digital Circuits (analog programmable via trimpots)
- Digitally Controlled Analog (analog programmable via computers or proprietary programming device)
- Digital Signal Processing (DSP), including those that employ special circuits (loudness mapping, electronic shaping, noise reduction algorithms, feedback and occlusion reduction, etc)
Other Important Circuit Options
- Multiple channels/bands
- Multiple memories
- Directional microphone systems
- Manual volume control/override or remote control
Important circuit options, as shown above, can include multiple bands, separate programs/memories (or automatically switching memories), and directional microphone systems that can substantially alter hearing aid performance and user satisfaction. Likewise, the actual programming of the aid is critical in defining what the device actually does (eg, it’s technically possible to program a digital aid to function as if it were a traditional analog linear aid). In the future, the above distinctions may become even more confusing as new software-controlled open-system and binaurally programmable hearing aids emerge. It’s even possible that digital instruments will end up replacing virtually all of the above circuit choices in the next decade; however, the variety of circuit/programming options within the digital category will probably be at least as extensive as the options present today. In other words, it’s unlikely that “circuit selection” will get simpler.
A large factor in hearing aid selection is price. Currently, with the addition of disposable hearing aids, the overall price per aid could range from $39 to $3600. Generally speaking, there is a direct relationship between sophistication of circuit design and cost. Therefore, among the patient’s options, there should be different prices for different features. The clinician, at this point, should include a plan to assess each individual’s need for what level of sophistication and signal processing is required to maximize the effectiveness of the hearing aid fitting.
One method to perform this element of hearing aid selection is to use a Needs Assessment Questionnaire. The construction of such a questionnaire should include different lifestyle/listening situations, cosmetic questions, cost factors, physical questions, and technology differences. In constructing such a questionnaire, the clinician should have particular models and fitting choices that relate to the actual questions. A sample of the first Needs Assessment Questionnaire used in my practice appears in Figure 3.
Figure 3. An example of a Needs Assessment Questionnaire that was used in the author’s practice. This questionnaire can take many forms, but often works best if each question is linked (positively or negatively) to a hearing aid category, style, technology, type, price range, etc, with the objective of zeroing-in on the most appropriate hearing aid.
The purpose of Needs Assessment is to reduce the multiple acoustical and physical options and merge them with the personal preferences of individual patient. In my view, no hearing care professional should refuse a patient’s personal choice if that individual has elected a specific model or technology—the obvious exception being a non-appropriate electroacoustic device (eg, a CIC model that doesn’t provide enough power for a person who has a severe hearing loss).
However, many patients—if not most—depend completely on the clinician to select the hearing aids for them. In this case, the clinician is in the position of having to make a fair and appropriate selection for that individual patient’s case. Often, higher-technology higher-cost hearing aids perform better than lesser technology, lower-cost aids. The hearing aid selection process needs to involve the personal needs of each patient, and this includes their financial situation. It is a fact that all fitted hearing aid amplifiers can provide some improvement of audibility and speech intelligibility. Included in the most important variables are under what circumstances will the patient usually be using the hearing aids, and why is the patient interested in purchasing the hearing aid in the first place? The goal of the Needs Assessment Questionnaire is to divine some of the critical wearing issues from the patient so that the dispensing professional can come up with the most appropriate device—one tailored specifically to their lifestyle and their needs, as well as their hearing loss.
This area of hearing aid selection requires more focus from the hearing aid research and professional dispensing communities. However, some tools have become available in the last several years. For example, the Hearing Aid Selection Profile (HASP)5 is a straight-forward 40-item questionnaire designed to assess the patient’s perceptions on cost, appearance, technology, physical function, and general lifestyle. In particular, it may serve as a good gauge of patient motivation and even have some predictive capabilities relative to patient outcome. Another example might be the Client Oriented Scale of Improvement (COSI).6 Although intended more for the hearing aid validation process than the selection process, the “unaided portion” of the COSI can serve as a good tool when ascertaining the most critical, salient listening situations that the patient came into your practice to solve.
Next in this series: It’s in the Numbers: Selection by Measurement, Circuitry, Components, and Expert Fitting Techniques.
Thanks to Jay B. McSpaden, PhD, for his thoughtful review and suggestions on this article. The author also thanks Gail Gudmundsen for the information presented in Figure 2.
|Joel M. Mynders, BC-HIS, is a hearing instrument specialist and educator. A graduate of William & Mary, he is owner and CEO of A.P. Mynders & Assoc., West Chester, Pa.|
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Correspondence can be addressed to HR or Joel Mynders, AP Mynders & Associates, Inc, First Digital Hearing Aid Center, 129 North Church St, West Chester, PA 19380; fax: (610) 436-5081.