The Guided Selection Method of Hearing Aid Fitting
By Gil Magilen, M.S., Ph.D
"The purpose of this and the referenced articles is to present a point of view which hopefully will serve the best interest of all of us in the hearing healthcare industry and our clients. A key consideration is that we have been working hard to fit hearing losses, rather than solve hearing problems. The difference between fitting a hearing loss and fitting a hearing problem is solely in our approach to serving the client, and this slight difference may mean tremendous change in our success. It is hoped that the ideas and methods suggested here might contribute toward the future growth of our industry." G.M.
ABSTRACT: A method is presented here in which the Hearing System Specialist (HSS) serves a s a knowledgeable, responsible "guide", who assists the client in selecting the best amplification to optimally fulfill the client's needs. Trying this method opens up the entire range of subjective problems facing the hearing impaired person. This provides an opportunity for inquiry and self-education for the HSS. Learning how to balance the subjective needs of the client is the "art" of dispensing. Learning how to provide the best technical improvement for the client, is the "science".
IN OUR INDUSTRY we often use the term "realistic expectations" for our clients. Unfortunately the goals we set for ourselves are often unrealistic with respect to what we are capable of doing. The industry abounds in goals sweeping from attempts to restore normal hearing, to "If they don't complain, I don't." There are miscellaneous prescriptive goals that have been tried. We'd all like to measure parameters of hearing loss, apply a proper formula, and send the client out knowing that they'll do just fine. Technically oriented dispensers have different goals from sales oriented dispensers. Manufacturers have different goals than academicians.
While obviously, there is no right way to fit a hearing aid system, there is a common denominator… the client. Interviews with clients revealed that the bottom line for clients with hearing problems is that they want their problems to be solved as best as they can be.
This paper presents an approach aimed at trying to solve the client's hearing problems rather than fitting their hearing losses. It is a method of addressing the subjective needs of the client, which demands the highest levels of objectivity and competence on the part of the Hearing System Specialist (HSS).
The method is called the Guided Selection Method (GSM). The concept of the Guided Selection Method is simple. The dispenser acts as a knowledgeable, responsible guide, who assists the client, in selecting the best amplification to optimally fulfill the client's needs.
The general goal of the Guided Selection Method is to optimize the individual's quality of hearing, to provide a "Natural" hearing experience with "Optimal" understanding in the everyday situations that have been causing the client problems.
Certain initial premises are made that act as tools toward achieving the goal of "optimizing the individual's quality of hearing". While the validity of each should be argued for each client, they function as guiding instruments towards our goal. They are as follows:
- The client should not have to adjust to a hearing aid: the hearing aid should be adjusted to the client.
- The client should have optimal speech understanding in all environments of concern to the client.
- The world as the client hears it should sound "Natural".
- The client should suffer not deleterious effects from the amplification.
- The client should want to wear the hearing aid system because the benefits should be evident and clearly outweigh the perceived negative aspects of wearing amplification.
Additional Criteria for a "Natural" Fitting
In addition, the client generally wants the following criteria to be met:
- To be able to comfortably understand the people they are interested in hearing.
- To have their own voice sound natural.
- Objects should sound like what they are: water like water, paper like paper, etc.
- Nothing should sound more intense than is comfortable. The client should not be so overwhelmed by the volume of sound that it impedes the client's ability to select the speech signals he/she needs in order to hear optimally. With eyes closed the client should be able to judge his/her distance of a common sound signal, such as a clang of glass or a hand clap.
- The client should want to put on the hearing system in noisy environments, because it helps.
- The earpiece should be comfortable from the beginning.
- The client should be able both to determine where a sound is coming from, and be able to focus his/her attention on a speaker of interest in a noisy room.
- The hearing aid should be inconspicuous and invisible to the client's self-image.
At the outset, the hearing system specialist relates to the client as a "guide" to assist the client in a search to obtain the best amplification to solve his/her hearing problems. The guide's knowledge, talent and experience are the tools he/she uses to serve the client. The trustworthy guide is one who works together in full communication with the client, and who uses honest judgements that are focused upon providing maximal benefit for the client.
Assessing Client Hearing Problems
When a client is asked the following questions the client will state his needs.
- Where do you have trouble hearing?
- 2. Who do you have trouble hearing?
- 3. When do you have trouble hearing?
- 4. When do others complain about your hearing?
- 5. What bothers you most about your hearing loss?
These hearing problems become the focus of the hearing aid selection process. The hearing problems should be listed on a chart and referred to regularly.
As much as we may hate to admit this, yet we do to every client, no hearing aid will correct an individual's hearing loss. While hearing instruments have come along way since the primitive amplifiers, they still cannot, as yet, simultaneously provide normal hearing thresholds with psycho-acoustically natural experience of all supra-threshold sounds for most people.
Moreover, even if they could, the non-acoustic limitations of the client, with regard to auditory processing abilities, could not be addressed by the hearing aid for all of the client's situations. The extent of the client's hearing problems are often too complex for the hearing aid to address them all.
By focusing in on the client's specific problems, optimal solutions can be constructed for certain average situations. This will no doubt be the place of the multi-program hearing aids in the market. Therefore, focusing upon the client's hearing problems limits the scope to be addressed with the hearing aid.
There is a wide spectrum of hearing aid users in the market. Some use hearing systems like an eyeglass wearer uses reading glasses or sunglasses. They may use them only when they "really want to hear something", or when they "go out" to a club where there will be noise. A large population use the hearing aids for specific purposed, for specific problem areas. Many clients, of course, wear hearing aids full-time and require a hearing aid balanced to include a broader range of factors.
Assessing the Client's Capabilities
Besides the audiometric hearing loss, many other factors must be appropriately balanced in order to successfully choose a hearing aid that will provide optimal use by the client. The following is a broad outline of a few basic concepts.
Physical/Anatomical Factors: From the physical structures of the ear to the dexterity of the fingers the client must be assessed for his/her capabilities to wear the different types of amplification. It is not unusual to find a great variability in structures and physical abilities in elderly individuals.
Mental/Social Factors: Hearing system specialists working with an elderly population are not surprised to see great variations in mental acuity and social activeness. If you had two clients with equal audiometric workups, one nervous and one as calm as a clam, would you choose the same amplification? Personality, social, and family responsibilities may play as great a role as the audiometric configuration.
Audiological Factors: As we know hearing losses can be categorized into sensorineural, conductive and mixed types. In my experience we cannot treat any of these hearing losses with sweeping generalizations.
Sensorineural hearing loss is a complex phenomenon of which our standard tests only scratch the surface. It is an attitude in our office that clients who present components of a SNHL are analyzed for sensorineural auditory processing syndrome (SNAPS). SNAPS, rather than being a confirmed anatomical or physiological disorder, is utilized as a measuring rod to assess the ability of a client to process auditory information. SNAPS will be discussed in greater detail in a later paper.
In addition to the standard battery of audiometric tests, simple discrimination, whisper, rapid speech tests at different S/N ratios and noise compositions can quickly indicate the value of differing types of amplification. They also help in estimating the possible degree of success in solving the client's specific hearing problems.
It is also important to keep in mind that the degree of hearing loss, mild, moderate, severe and profound, are each categories unto themselves. What we learn from experiments with individuals with severe losses, with regard to gain and output characteristics for example, cannot be extrapolated to individuals with mild or moderate losses.
Hearing Threshold: Provide functional gain to a sound field threshold of 25 dB HTL from 250 Hz to 4 kHz.
Supra-threshold Intensities: Common sounds should be experienced as natural. Each bit of amplitude/frequency/time/phase information should be experienced by the client as appropriate to the object.
The above "hearing threshold" and "suprathreshold intensity" objectives should be over-ridden in any case where modifications would place the client at an advantage in comfortably solving his/hear hearing problems. (This statement demands the highest levels of competence and ethics from the HSS.) The author is not unaware that incompetent, unethical dispensing individuals could point to this statement to justify "under-fitting" in the name of "problem solving". It is only appropriate to employ the concepts of "optimal audiometry" if the HSS includes in writing his/her client's portfolio, a statement from the client, that the client is aware, from the outset, of the restricted limits of the hearing system and freely chooses to purchase the hearing system because it satisfies their particular needs.
Determination of Audiometric Benefit
Proper sound field measurements provide the most accurate verification of the actual functional gain a client is receiving. It is a direct measure of aided hearing threshold.
Speech discrimination in noise (similar to the situation the client experiences) is the second best determiner of aided benefit. The best is actual trial period use with a particular setting.
Prior to selecting a particular hearing aid system, the HSS must determine the possible degree of success of various types of amplification. Using either a Master Hearing Aid, stock hearing aids and molds (or making an earmold in some cases), the HSS must determine precisely the best way to apply the amplification for this individual, irrespective of whether or not the client wants to wear that type of amplification or not.
The HSS must determine a variety of gains, frequency responses, output levels, compression characteristics, ventings, multi-program features, and aid types, to demonstrate to the client (for them both to analyze) the effectiveness of each at addressing the stated hearing needs and problems of the client.
Different audiometric configurations must be demonstrated in mock environments to determine the best possible solutions for the client's problems.
Selecting the Hearing System
The client should be introduced to the range of hearing instrumentation available on the market. The benefits and limitations of each should be presented clearly and thoroughly, keeping in mind the eight selection criteria for quality and what is needed to maximize audiometric benefit. The client thus informed, chooses the type of amplification he/she feels would best serve his/her needs, to try on a trial basis.
Fitting the Hearing System
The following system of approach is used in our office to fit any hearing aid system, or mode of a multi-program instrument.
Comfort. The hearing system is first adjusted for physical comfort.
Hearing. The hearing system is adjusted to maximize their hearing threshold level while retaining a natural experience the intensity of normal speech.
Quality of sound. Output is regulated so that common objects sound natural to the client.
Binaural balancing tests. The intensity and quality of a whisper, shout, or normal level speech, should be experienced as equal on both sides by the client.
Noise tests. Loud noises, party noise, and mock problem environments are presented.
Distance hearing tests. Male and female voices are presented at twenty feet.
Multiprogram aids. Each program must be custom fit to a simulated environment, and the client must be able to understand when and how to switch to the appropriate program.
A Word about User Adaptation
Some users adapt; others do not. Clients should not be asked to adapt more than they need to in order to comfortably address their hearing needs. Follow-up analyses of clients have demonstrated that while many will learn to accept and even benefit from the over-amplification of certain sounds, others, 5-8 years later, are still resistant to additional amplification.
Over-amplification is defined here as presenting sounds at a psycho-acoustically experienced level higher than they appear in the natural environment. The reason to over-amplify is to place the client at a hearing advantage, to optimize a situation for a client.
It is the author's opinion that such over-amplification should be cautiously applied, with full consideration of the detrimental effects of amplified sound on the progression of sensorineural hearing loss.
Judgment and Compromise
As stated above, no hearing aid system is capable of acoustically correction for an individual's hearing loss providing normal hearing thresholds and supra-threshold experiences. Therefore the audiometric choices as to where best to apply the available amplification call for intelligent judgment and compromises.
In the past such judgments were governed by audiometric "prescriptions" based upon group studies. The client would end up with an average fitting, and if the client complained the prescription was modified by the dispenser.
This paper aims to focus the judgments and compromises, from the outset, on the specific hearing problems and capabilities of the client. Using his knowledge, the HSS customizes the hearing aid system for the comfort and maximum benefit for the client's hearing problems.
Verification of the Audiometric Benefit
Audiometric benefit is determined in the office by sound field audiometry (or a real ear system with true, proven, decibel accounting), an by speech discrimination in noise tests.
After the fitting, the client is instructed to rate how well the following goals are reached and the degree of success at solving their original list of specific hearing problems.
A card with the following list should be explained, item by item, so that the client understands them and is able to rate the degree of "naturalness" of the item. (These were stated earlier in the section, "Additional Criteria for a Natural Fitting").
- Understanding others: Peoples' voices should be clear and natural sounding (not echoey, muffled, in a barrel, tinny or loud).
- Experience of own voice: The client's own voice should be clear and natural sounding (not echoey, muffled, in a barrel, tinny or loud).
- Experience of common sounds: Objects should sound like what they are: water like water, paper like paper, etc.
- Control of loudness: Loudness is divided into three experiences.
- Intensity: Nothing should sound more intense than is comfortable. Once set the client should not have to lower the volume control to avoid commonly loud sounds.
- Volume: The breadth of sounds should not overwhelm the client's ability to select out the speech signals he/she needs in order to hear speech.
- Distance: With eyes closed the client should be able to judge his/her distance from a common sound signal such as a clang of a glass or a hand clap.
- Control of background noise: The client should never do better with the hearing aid off in a noisy environment. The client should want to put on the hearing system in noise.
- Comfort of earpiece: There should be no discomfort from the beginning. The distraction of wearing the hearing system should pass in less than a week.
- Directionality: The client should be able both to determine where a sound is coming from, and be able to focus his/her attention on a speaker of interest in a noisy room.
- Appearance: The hearing aid should be inconspicuous and invisible to the client's self image.
The Trial Period
The purpose of the trial period is to verify the extent of both the benefits and limitations of the chosen hearing aid system. The "guiding" HSS sends his client, "the scout", out to look for benefits and problems. The client returns and reports on "naturalness" of the eight characteristics, and on the success or failure of the instrument at solving the client's hearing problems. The HSS must apply his/her technical knowledge to modify or change the hearing aid system as best it can be in order to address the concerns of the client.
The client is instructed to return until there is no longer a reason to return. If the instrument is tuned to its best capabilities, and to the best capabilities of the HSS, then this should be acknowledged and the HSS's role is completed.
The Statement of Confirmation of Benefit
In some manner, the HSS must have a written statement from the client that the client, after thorough evaluation, is satisfied with the improvement in hearing quality that he/she receives with the hearing aid system.
A Challenge and an Opportunity
Trying this method opens up the entire range of subjective problems facing the hearing impaired person. This provides an opportunity for inquiry and self-education for the Hearing System Specialist. Learning how to balance the subjective needs of the client is the "art" of dispensing. Learning how to provide the best technical improvement for the client is the "science".
The author wishes to acknowledge the support of many friends in the Audiological and dispensing communities, and also the National Institute of Aging, National Institutes of Health, U.S. Department of Health and Human Services, providing a grant to study the audiologic problems of the elderly.
Magilen, Gil, MS, Ph.D - The Real Hearing Aid Market, Hearing Centers' NetworkTM, 1990 P.O. Box 7189, Vallejo, CA 94590
Magilen, Gil MS, Ph.D - A Need for Knowledgeable, Responsible Hearing System Specialists, op. cit.
Dr. Gil Magilen has an MS in Physiology and a Ph.D in Biophysics. He was a research neurophysiologist at the University of California Medical Center in San Francisco, working under grants from the National Institute of Aging, prior to entering private practice in 1982. He developed an office management software called MacHearTM, and has founded Hearing Centers' NetworkTM for the exchange of practical information within the hearing healthcare community.
Natural Versus Optimal
The words "natural" and "optimal" are often used in the Guided Selection Method. Understanding their meaning is essential.
Natural is defined as "nothing artificial added". A hearing aid sounds natural when it accurately reflects the external environment. Even though an individual with a hearing loss may not perceive sounds as a normal hearing individual does, he/she knows when it is excessive. If it is just a unique or an unusual sound, as the wearer becomes familiar with the sound (after using the aid for a short while) he will classify it as new, but natural. If it is excessive, the client will not accept it as being natural.
Optimal means that which provides the best, most favorable hearing, given all of the factors that need to be balanced. It is not unusual for natural and optimal to conflict. An optimal level for TV understanding may not be at a natural level of sound.