Bottom Line Conclusions from our Publications
Current generation hearing aids are capable of dramatically increasing a hearing impaired individual's ability to understand speech under a wide range of listening conditions, but only if they are properly programmed. (See Missing Link (2004) slide presentation, Missing Link (2005) publication)
Practitioners need to be trained in the skills and knowledge required to achieve optimum hearing benefit from today's state-of-the-art digital hearing aids. (See: Proposal to the FDA (2004)
Be cautious and informed prior to purchasing hearing aids. The best way to verify the benefit hearing aids provide is to take them off in each of your listening situations. How do you perform compared to the normal hearing people around you? (See: What to expect from hearing aids , Dr. Gil's Whisper Test , Dr. Gil's Hearing in Noise Test)
The marketing of hearing aids appeals to cosmetics, price and the illusion that newer means better.The newer hearing aids provided with the standard "hearing loss" prescriptions do not improve speech intelligibility in noise better than older technology. (See: Missing Link (2005) publication)
Detailed programming (fitting) of hearing aids is extremely important to achieve optimal benefit. Small changes in the presentation of sound have dramatic effects on speech intelligibility and the ability to separate speech from noise. (See: Effect of Small Changes of Acoustic Energy on Real World Performance with Hearing Aids)
Abstracts of Our Papers
Magilen, G. ( 2007)- "Effect of Small Changes of Acoustic Energy on Real World Performance with Hearing Aids"
A most consistent finding in all studies correlating sensory, neural or cognitive processing and their relation to speech intelligibility in the hearing impaired is the broad distribution of the performance of individuals on all such tests. This reduced speech intelligibility is due to unique individual differences and deficits in the operation of their sensory, neural and cognitive processing.
The only publication of a highly significant improvement in speech intelligibility in noise required individually programming hearing aids to address each individual's sensory, neural and cognitive capacities (Magilen & Greenberg, 2005). It reported in -5dB SNR conditions using the same directional hearing instrument that speech intelligibility was improved by 48% over the standard method of hearing correction. The global noise reduction and speech processing algorithms and other "advanced features" incorporated into current digital hearing aid devices, on the other hand, do not improve speech intelligibility by even 1% significantly, in noise over the old non-digital aids.
This paper presents a case study that demonstrates the unique character of an individual's hearing impairment and the need for subtle, individual, detailed correction to provide functional benefit. It demonstrates variation in the spectral, temporal, intensity, spatial, cognitive and experiential dimensions.
"Hearing-impaired" individuals have unique disturbances throughout their auditory and language processing space. Speech processing is a purposeful, simultaneous, multi-level, multimodal, multi-dimensional, multi order scalar, operation on acoustic spectrotemporal information. Age reduces the speed and accuracy of brain processing. It consequently affects the coordinated temporal processing necessary to make rapid speech intelligible and separated from environmental sounds. The disturbances become more complicated as the individual ages.
Hearing loss unmasks a multitude of auditory processing deficits that otherwise go unnoticed due to the otherwise robust capabilities of normal speech decoding mechanisms. This appears to explain why a small loss in audibility can have large loss in speech perception. Prior to their speech perception difficulties, certain individuals depended greatly upon those fine elements of acoustic energy.
This observation reinforces the concept that optimal speech intelligibility and speech separation from noise for hearing-impaired individuals is dependent upon the detailed placement of fine elements of acoustic energy uniquely for each individual ear. It argues against the indiscriminate manner in which hearing aids are currently provided.
Presentation at Temporal Dynamics in Speech and Hearing, Antwerp, Belgium (2007)
Magilen, G. & Greenberg, S. (2005)- "The Missing Link - "The Importance of Diagnostic and Fitting Strategies for Clinical Amelioration of Hearing Loss Using Digital Hearing Aid Technology." Twenty First Danavox Symposium
It is the thesis of this study that current-generation hearing aids are capable of providing substantially greater benefit if only the methods by which they are fit were substantially revised. In particular, we demonstrate that the ability to understand spoken language in noisy backgrounds improves dramatically when the fitting procedure is adapted to take into account more than just factors related to audibility and loudness.
There are two general types of variable each of which is important to delineate in testing the hearing impaired. One type is observable, the other hidden. The readily observable parameters are (1) audibility, (2) loudness, and (3) intelligibility. The hidden parameters are (1) loudness perception linked to sensory scene analysis, (2) spectral and temporal distortions, (3) spatial distortions and (4) a multitude of cognitive distortions. Such cognitive distortions pertain to the brain's ability to resolve signals in the presence of competing sensory signals and are extremely important for achieving optimum benefit. Conventional fitting procedures focus on the readily observable variables, but usually neglect the hidden parameters. However, for speech intelligibility to be optimized it is essential to fine-tune all of the hearing aid's settings using the hidden parameters.
Individuals vary tremendously with respect to both the hidden and apparent parameters. There is far greater variability among the hearing impaired than is commonly acknowledged. Other sources of variability include the ability to adapt to the hearing aid over time and the ability to exploit dynamic acoustic information across the frequency spectrum and over a range of sound pressure levels. Such variability is difficult (if not impossible) to accommodate within an automatic fitting procedure. Instead, the hearing aid practitioner must customize the fit to the client's unique auditory-cognitive profile.
These data suggest that the fitting formulations prescribed by manufacturers focus on understanding speech in quiet, but are ill suited to backgrounds (such as speech babble) posing the greatest challenge to the hearing impaired. In contrast, HCN's fitting methodology provides relatively high (and stable) intelligibility for all subjects under comparable conditions.
21st Danavox Symposium pps: 375-385 (2005)
Magilen, G. (2004) - United States Patent # 6674862 - "METHOD AND APPARATUS FOR TESTING HEARING AND FITTING HEARING AIDS"
ABSTRACT: A system and method for testing hearing or for testing and fitting hearing aids is provided, which includes at least one, and preferably a plurality of, compound multi-channel dynamic filters. The system is equipped with earphones, enabling the test operator to hear sounds transmitted to the subject simultaneously with the transmission. A signal is transmitted to the test operator that representing a condition in the patient's ear canal or canals. The test operator modifies the signal using the filter or filters to produce a transmitted signal conforming to and indicating the hearing loss of the subject. This information may then be used to adjust or fit a hearing prosthesis as appropriate, and can also be used to recognize a situation in which the subject's hearing is normal but the subject has lost capability to process sounds.
United States Patent # 6674862
Magilen, G. (2004)- "The Missing Link - The Importance of Diagnostic and Fitting Strategies for Deriving Optimal Benefit from Digital Hearing Aids." Slide presentation
Current hearing aids can provide a dramatic increase in speech intelligibility in noisy environments, the primary concern of the hearing impaired
The Missing Link is the clinical practitioner who possesses the skill and knowledge required to achieve optimum hearing benefit from today's state-of-the-art digital hearing aidsBack to Top
Magilen, G. (2004)- "Hearing-Aid Consumer Action Proposal to FDA: FDA Oversight of Hearing-Aid Technology Should Be Strengthened Not Weakened."
The FDA is urged to enhance (rather than reduce) oversight of the hearing-aid industry by establishing a hearing-impairment awareness program and by raising the standards and practices that govern the marketing and dispensing of hearing aids in the United States. Particular emphasis should be placed on the methods by which hearing aids are fit, as well as the technology used to evaluate and tune the devices. The ultimate objective should be to inform patients and to optimize the benefit afforded by the hearing aid so as to enable the patient to achieve the fullest possible communicative potential as a means of maintaining (or even enhancing) his/her quality of life.
Document sent to the FDA (2004)
Magilen, G. (1994)- "Maximizing Sound Quality and Audibility with Hearing Aids - A Direct Approach to User Satisfaction."
This paper introduces the theory and technology of how to directly utilize a client's subjective experience in the fitting of hearing aids. A thorough knowledge of instrumentation and acoustics is a prerequisite. The method defines concepts of "natural," context, auditory objects, clarity, etc. to extract useful information from the client's report of their auditory experience. That information is then used to select and adjust hearing aids. A carefully monitored field evaluation period verifies the efficacy of the fitting and assists in establishing realistic expectations for the client. The goals of "natural sound quality" and optimal audiometric results are not mutually exclusive. This is demonstrated by both objective measures of successful fittings, as well as other measures of client satisfaction.
The Hearing Review 2(5): 32-35 (1994)
Magilen, G. (1993) "Critical Analysis of the Hearing Healthcare Industry"
The state of hearing healthcare in America is the result of problems with all participants in the hearing healthcare community: audiologist, physicians, manufacturers, the trade journals, and dispensers.
Audiologists: There are two problems with the audiological community, one an ontological problem regarding the development of the basic audiological concepts, and the other a practical problem regarding audiologist's current capabilities for dispensing hearing aids.
Physicians: The medical community has neglected hearing problems in the elderly.
Lacking adequate knowledge of both hearing impairment and possible hearing aid benefits, physicians are reluctant to precede referring patients in a direction that may have unsuccessful outcomes.
Manufacturers: Manufacturers have to sell hearing aids to survive and they find solutions to assure survival irrespective of the knowledge level of the audiologists or the competency of the dispensers.
To solve the problem manufacturers learned to create the small hearing aids people will buy and that the dispensing community can sell.
In conversations with manufacturers it is their opinion that the average dispenser or dispensing audiologist does not have the technical background to expertly fit a hearing aid.
Trade Journals: The trade journals have a co-dependency relationship with the manufacturers. They do not publish papers that are objectively critical of manufacturer products or that give an objective analysis of the status of the industry.
Audiological journals as well do not provide objective research on hearing aids.
Dispensers: Generally dispensers can be roughly classified into three categories: sales-oriented, technology-oriented, and people-oriented.
While most dispensers are interested in finding real solutions for their clients, there is definitely a sales-oriented population who are more interested in profit than in service.
No segment of the hearing healthcare community has the moral high ground, nor deserves the right to wear the white hat for the hearing impaired.
Personal communication to David Kessler (1993) Back to Top
Magilen, G. (1993) - "The Basis of Hearing Aid User Dissatisfaction"
Why, fundamentally, do people complain that they are dissatisfied with their hearing aids? To understand the answer to this question requires a deep appreciation of what is occurring to the ear and brain of the "hearing impaired" elderly.
I wish to address a deeper question to try to understand why more people are dissatisfied with their hearing aids than with their eyeglasses even when they are fit in the most responsible of ways.
Personal communication to David Kessler (1993)
Magilen (1993) - "Cover Letter to FDA Commissioner David Kessler"
Papers sent to investigating FDA Commissioner David Kessler in 1993 after the AARP presented their report to the Senate Special Committee on Aging indicating "the relatively low level of satisfaction among long-time, regular users of hearing aids":
"I believe [the FDA] is overlooking the big picture of why the hearing healthcare industry as a whole is not successfully meeting the needs of the large hearing impaired population in America.
After a literature search, and interviews with audiologists and dispensers, it became clear to me why people were dissatisfied. The methodology or knowledge of how to successfully fit hearing aids so that hearing impaired people truly benefited was not available. Personal experience, discussions with clients, manufacturers, physicians, academics, and trade journal editors corroborated this conclusion."
Personal communication to David Kessler (1993)
Magilen, G. (1990)- "The Real Hearing Aid Market"
The Bottom Line is: People don't buy hearing aids because they have a hearing loss, but because they have a significant, correctable hearing problem.
The absence of growth in the hearing aid industry is explained in terms of (1) a 25-50% smaller market than previously reported in the industry literature, (2) the observation that hearing aid owners (more than 50%) do not buy replacement hearing aid systems, (3) a hearing aid replacement rate (by those replacing) of five years instead of three, (4) unrealistic expectations for hearing-impaired individuals, and (5) unrealistic expectations for those in the dispensing community.
When does a hearing loss become a hearing problem? Probably only when the individual or his significant others recognize it as such. Just because a particular level of hearing is mathematically outside of a norm, or an arbitrarily defined "low fence," this does not indicate that the individual is significantly impaired, from the individual's own point of view.
We shouldn't forget that the audiometric standards for evaluating the degree of hearing loss were for the utilitarian, medico-legal purposes, not for determining actual individual impairment, which is notably complex. For Hearing Aid Industrial purposes we need to know when does a hearing loss become a hearing problem for the individual, and, when do we have the capabilities of aiding that individual with his/her problem.
It should be noted that 16 individuals came into our office complaining that their hearing losses were a problem some or most of the time, and these individuals measured as bilateral normals. It is even difficult for the individual to recognize the actuality of a hearing loss, as opposed to a hearing problem that he/she may have.
SNAPS. The sensori-neural auditory processing disability of an older client may not allow the client to successfully discriminate speech, especially in noise, even with a hearing aid system. While younger clients can compensate for the inaudibility of certain sounds, the older person is not so fortunate. Many older individuals, especially those with sensori- neural hearing losses (SNHL), can be described as having more a hearing syndrome than a hearing impairment. A hearing impairment implies that improving the hearing will solve the individual's problem, however we know that this is not the case.
Many older individuals have sensori-neural auditory processing syndrome (SNAPS). Besides the decrease in audibility of sounds with age, often, older individuals with SNHLs process speech more slowly, are less attentive, can accommodate new sounds less easily, are more distractible, irritable, less interested, etc. Without the mental tools necessary to take advantage of the new sounds given to them by the hearing aid, the older individuals may find themselves less motivated to try the benefits of a hearing aid system.
It appears that long-term sensori-neural impairment tends to have retrograde effects not only physiologically, but also in information processing at the central level. Poor discrimination in noise, poor discrimination in quiet, increased sensitivity to loud sounds, all contribute to a syndrome whose affects must be sensitively addressed by the dispensing professional on an individualized basis with the client.
It is not a surprise to find that such individuals with SNAPS, especially those with mild-moderate losses feel that a hearing aid "will not help their particular type of hearing problem" as said in the HIA report. The problems they are facing are significantly more complex than the inaudibility of speech sounds.
Hearing Centers Network Publication (1990)
Magilen, G. (1990)- "A Need for Knowledgeable, Responsible Hearing Systems Specialists"
It is the author's belief that the hearing aid industry needs a new type of Hearing System Specialist and that the focus of this professional is neither merely fitting the parameters of the hearing loss nor pacifying the client with some amplification. The focus is to discriminate the specific hearing problems of the client, the capabilities of the client, and to select with the client the most appropriate amplification that would fulfill the client's need. When a client comes into a hearing aid dispensing facility, the most important thing the client is paying for is the valuable knowledge of the individual who assists the client in the proper selection of the client's hearing aids.
A Need for More Education: Quality Hearing System Specialists are created through an education broader than that currently obtained in audiological programs. The practical knowledge gathered through dispensing experience as well is not enough. Besides the standard audiometric/dispensing course materials, four areas must be addressed in greater detail: (1) understanding auditory processing in the elderly, (2) understanding the acoustics of speech and the noise environment, (3) understanding how to apply the available forms of amplification to specific situations, and (4) how to discriminate the real advances in hearing aids and audiometric instrumentation technology from advertised claims.
Understanding Auditory Processing in the Elderly: Auditory processing has always been reserved for academicians. However, studies of the physiology of hearing and of speech processing are invaluable in assessing the capabilities of the sensori-neural hearing loss individual. Appreciating the factors in both the ascending and descending neural pathways provides insights into what a particular client is able to extract from the acoustic information and how well they are able to focus on the incoming sounds of interest. A mere delineation of the parameters of speech processing can give the HSS an appreciation of what the special needs and capabilities are of his/her SNHL client.
Understanding Speech Acoustics and the Noise Environment: Every room has different acoustics, different generators of sound all with different amplitudes, frequencies, and time and space patterns. Every individual of interest to the client has a different speech pattern. We have just gone through a period when each manufacturer defined "noise" in a particular way and then developed a hearing aid to handle that sound. Again, like the ten blind men describing the elephant, while each could successfully control its particular type of noise, the aid fell short in controlling a vast number of other noisy situations. By understanding the client's environments, the qualities of voice of his/her significant relations, the dispenser can choose amplification tailored to the client's specific needs.
Now with the advent of multiprogram hearing aids, each setting can be specifically tuned to best handle specific situations, for those clients capable of using and appreciating the different amplification modes.
Understanding How to Apply the Available Forms of Amplification: At any point in time, the HSS has available a smorgasbord of types of amplification differing electroacoustically, in size and shape, in the availability of special features. While no manufacturer can address the needs of all clients, the HSS must know how to choose the most appropriate form of amplification. This requires an understanding of the capabilities and limitations of each form of amplification and how and when to best apply that amplification.
Understanding How to Discriminate Real Advances in Hearing Aid Instrumentation Technology From Advertised Claims: The hearing aid industry is not a science with rigorous reviews and restrictive controls to assure accuracy of data and claims made. Nor is it a large market with a multitude of diverging opinions and critical analyses by competing and independent sources. The HSS him/herself is the one in the position to determine whether the claims about a product or instrument are accurate. He/she must purchase and invest without the benefit of critical reviews. To do this takes a great discriminating ability and a vast knowledge of the instruments, or it becomes a "trial and error" activity. Unfortunately, the errors can be costly for both the dispenser as well as his client.
Hearing Centers Network Publication (1990)
Magilen, G. (1990)- "The Guided Selection Method"
A method is presented here in which the Hearing System Specialist (HSS) serves as 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".
Audecibel 40(1): 16-20. (1991)