8 Hearing Aids: Considerations in the Geriatric Population
Introduction
Hearing loss is the most common sensory deficit in the elderly.1 Hearing loss can impair communication, thus creating loneliness, isolation, dependence, frustration, and even communication disorders.1 When left untreated, hearing loss can substantially impair quality of life. Audiological rehabilitation, auditory rehabilitation, and aural rehabilitation are often used interchangeably to describe a patient’s management process designed for individuals who experience deficits in communication, as reported by Weinstein.2 Functional capabilities must be assessed on an individual basis due to wide variations in characterizing elderly adults. Chronological age is not a reliable predictor of physical, social, or mental status; therefore, it is important to understand how individuals view themselves. The impact of hearing loss varies by the degree of loss and the individual’s personality and activity level. The effects of hearing loss cannot be restricted to pathology alone because the mechanics of the ear cannot be isolated from the social aspects of hearing. The personality effects of hearing loss are largely dependent on an individual’s character, including mental, spiritual, societal, and economic resources. These components determine one’s reaction to hearing loss and the level of handicap it generates. Rehabilitation in the elderly must include a comprehensive approach to assessment and a multidimensional intervention. The purpose of rehabilitation with older adults, regardless of the severity or type of impairment, is to assist in recovering lost physical, psychological, and social skills.
The entire auditory system undergoes considerable change as the aging process progresses. Specific conditions may affect the type of aural rehabilitation to provide. For example, older adults develop changes of the outer ear and external auditory canal due to thinning of the epithelium, atrophy of subcutaneous tissue, and decline in secretory abilities of the glands. Hence certain types of hearing aids or audiological testing may not be appropriate due to changes in the ear structure. Although outer and middle ear pathologies are monitored under the care of a physician, the audiologist should be aware of any such issues. It is important to consider age-related changes in the brain when determining auditory rehabilitation in the elderly population. Aging is associated with progressive losses in function across multiple systems, including sensation, cognition, memory control, and affect. Age-related modifications in the central nervous system are associated with declines in the ability to perform selected cognitive and sensorimotor tasks; decreased functional capacity; and alterations in gait control, learning, and memory.3 These deficits may affect the patient’s ability to respond to aural rehabilitation strategies.
Hearing loss may be severe in older persons, whether from causes associated with aging or owing to other etiologies. More severe-to-profound losses may be associated with a change in personality and lifestyle due to the challenges that listening presents. Elderly individuals with hearing loss also find listening in the presence of multiple speakers or background noise especially difficult because their ability to detect signals in noise diminishes with age. All too often, the elderly person begins to believe that the inability to hear and understand a conversation is due to deterioration of the brain (intellectual impairment). Family, friends, and stereotypes of the elderly population may reinforce this belief. People may ignore the hearing-impaired person in group conversations and assume that the person does not know what is going on. Stereotypes of aging, such as physical and mental slowing, further undermine the elderly person’s weakened self-confidence and hasten his or her withdrawal from society. The isolation caused by hearing loss can contribute to delay in elderly individuals’ seeking medical attention to address their hearing handicap.
There is a significant relationship between hearing and speech. The ear is sensitive to a certain frequency range, and speech falls within that range. Speech can be divided into two types of sounds: vowels and consonants. Roughly, vowels fall into the frequencies below 1,500 Hz, and consonants above 1,500 Hz. Vowels are relatively powerful sounds, whereas consonants are weaker sounds and are dropped often in everyday speech or not pronounced clearly. In essence, low-frequency speech sounds provide the listener with a sense of volume, whereas higher-frequency speech sounds provide meaning and clarity. Most commonly, older adults experience a hearing loss configuration that reflects comparatively good low-frequency hearing and poorer high-frequency hearing. High-frequency sensorineural hearing loss often causes deterioration of a person’s ability to understand speech. Speech recognition ability can be correlated with the aging process.4 In some cases, diminished speech understanding is due to peripheral hearing loss. This type of loss typically presents with the ability to hear speech but not understand it. A second cause of trouble understanding speech is central auditory processing issues, such that age-related changes or other changes in the auditory pathways of the brainstem or portions of the auditory cortex degrade the speech signal.5 Individuals with hearing loss may ask people to speak louder in an attempt to achieve better speech clarity. Unfortunately, “louder” is not always the answer. Loudness may actually reduce discrimination ability due to distortion of the speech signal. Distortion occurs more frequently in people with high-frequency hearing losses because overall loudness also amplifies the low-frequency sounds, such as vowels, which they usually hear at a normal or close to normal volume. Speaking in a louder voice creates overpowering vowels with relatively weaker consonants and does not improve the clarity of speech. These factors must be assessed and are critical to proper hearing aid selection.
Before a hearing aid is recommended, it is necessary to determine whether the patient will be helped by it enough to justify purchasing one. Hearing aids are generally not covered by Medicare; however, Medicaid or private insurance plans may cover the cost of hearing aids in whole or in part. Regardless of insurance type, patients must be offered the same services, the cost of the services must be equitable, and national procedure codes must be used for requesting reimbursement. It is important to assist the elderly patient in figuring out what his or her specific insurance will cover, if anything, before proceeding with purchasing hearing aids. For those patients that have served in the military, it is advisable to obtain amplification through the Veteran’s Administration because hearing aids and other assistive devices are fully covered through veteran’s benefits. Both economic factors and individual hearing loss should be taken into account. This is particularly important in a sensorineural impairment in which the problem is more one of discrimination than of amplification. Typically, high-frequency sensorineural hearing loss is attributed to presbycusis—age-related hearing loss that is associated with the cochlear degenerative process of aging. Humes et al reported that the hearing loss of older adults is greatest in the frequency region (≥ 2,000 Hz) for which the amplitude of speech is the lowest.6
Beyond presbycusis, there are also medical causes of hearing loss, including infection, autoimmune disease, medication effects, and many other conditions. These causes should always be evaluated by a physician, and medical causes of hearing impairment generally should be treated in conjunction with auditory rehabilitation and amplification for every patient. A patient being considered for a hearing aid should undergo otologic evaluation first.
Hearing Aid Considerations
Hearing aids, assistive listening devices, and implantable devices may be helpful for older adults with hearing loss and communication issues. A hearing aid is a portable personal amplifying system used to compensate for a loss of hearing. Almost all hearing-impaired patients are candidates for a hearing aid, although some will receive greater benefits from their aids than others. Any patient who is motivated to use a hearing aid deserves a thorough evaluation and a trial with an appropriate instrument. Assistive listening devices include amplified telephones, television amplifiers, and other such tools that can increase signal intensity for the listener. Implantable devices can include bone-anchored hearing aids, cochlear implants, and the auditory brainstem implant. Hearing aids are appropriate for the vast majority of patients, and this chapter does not address cochlear implants or auditory brainstem implants.
According to Kochkin, the average age of new hearing aid users is 71.1 years.7 Of the 34 million people with hearing loss in the United States, only 25% use hearing instruments, which suggests that over 25 million people are living with untreated/unaided hearing loss.8 Despite recent advances in hearing aid technology and miniaturization of hearing aids, negative attitudes persist. Before fitting a hearing aid in an older adult, various factors must be considered, such as communication, physical, psychological, and sociological factors. Some of the issues older adults face when considering use of hearing aids include the following:
1. Experience with hearing aids
2. Financial considerations
3. Attitudes toward hearing aids
4. Degree of hearing loss
5. Lack of need
6. Visual/manual dexterity issues
7. Recommendations from professionals
8. Recommendations from family and friends
9. Stigma
10. Trust
11. Lack of knowledge.
The audiologist is responsible for informing patients fully about the entire process and providing realistic expectations, counseling, and support before fitting a hearing aid.
Prefitting Assessment
The audiologist must administer tests to determine whether a hearing loss is present and, if so, the nature of the hearing loss. Threshold measures used in conjunction with otoscopy and immittance testing can help determine the need for medical or surgical remediation. If a condition requires immediate medical attention, the patient should be referred to the appropriate medical professional. Regardless of any degree or nature of impairment, medical clearance for hearing aids from a physician should always be obtained. If no medically treatable condition is present, the severity of hearing impairment, symmetry, configuration, type of hearing loss, and speech perception should be documented. Once medical contraindications are ruled out and the patient is determined to be a candidate for amplification, the audiologist must discuss thoroughly the nature of the hearing loss, its consequences, and realistic expectations, and must evaluate personal factors and the patient’s motivational level to use amplification.2
The patient should be given a clear explanation of the hearing problem and why he or she has trouble hearing or understanding speech. Patients should understand the difference between hearing difficulty and understanding difficulty, and how amplification affects both. The problems that might easily lead the patient to develop frustration and behavioral changes should be explained clearly so that these problems can be met forthrightly and intelligently. The goal of aural rehabilitation is to prevent or mitigate psychosocial changes and quality-of-life impairments that may result from hearing loss.
Psychological adjustment for each patient involves giving the patient more penetrating insight into the “personality problems” that are already in evidence or likely to develop as a result of hearing loss. Therapy should not use a predetermined technique but must be designed to meet the needs of the specific hearing-impaired individual. Frequently, it is advisable to implement aural rehabilitation not only with the patient, but also with the patient’s spouse or family because it is impossible to separate a person’s individual problems from family problems. The patient must be encouraged to associate with friends and not become isolated because of difficulties in communication. It must be impressed on individuals that using residual hearing effectively allows them to enjoy life and interact as usual with only minor modifications. Use of questionnaires can be very helpful during the prefitting assessment. The Hearing Handicap Inventory for the Elderly Screening Version described by Weinstein (HHIE-S) is a good tool for determining patients’ perception of their hearing loss.2 The HHIE-S is a 10-item questionnaire developed to assess how an individual perceives the social and emotional effects of hearing loss. A higher HHIE-S score suggests a greater handicapping effect of a hearing impairment.2 The information obtained from this questionnaire can help the audiologist tailor counseling and intervention strategies.
As discussed previously, speech discrimination problems experienced by older adults often have a central auditory or cognitive basis. Because this issue has been identified, part of amplification candidate selection should include a test battery that at least screens for central auditory processing disorder (CAPD). A relationship between sensorineural hearing loss and cognitive impairment has also been identified.9 It can be difficult to separate cognitive and central auditory effects from peripheral effects in the elderly. Recent data suggest that central auditory dysfunction may be an early manifestation of more general cognitive impairment and therefore may be a contributing factor to poor performance of older adults.10
Physical Factors
In the elderly, vision status, manual dexterity, ear/ear canal variables, and overall health status should affect the hearing aid decision process.2 Vision problems may dictate the choice of hearing aid design, style, and type of signal processing. Otologic issues such as excessive wax buildup, active infections, stenosis of the external auditory canal, or unusual growths (such as exostoses) can inhibit the insertion of a hearing aid or limit the effectiveness of a specific style of hearing aid. Patients with a tendency to accumulate excess earwax should be acquainted with options for controlling earwax so that it doesn’t affect hearing aid performance. Wax buildup inside of a hearing aid can impair the overall sound quality. Acute middle ear problems such as active infection or effusion can also contraindicate hearing aid use until the problem is resolved. Acute otitis externa will prevent use of a hearing aid until the infection is cleared as determined by their physician. In all cases of suspected medical pathology, patients should be urged to seek medical intervention.
Today’s digital hearing aids are considerably smaller than the older technology. Smaller hearing aids can pose a challenge for many older adults who may suffer from poor vision, reduced manual dexterity, diminished tactile sensitivity, or reduced fine motor coordination.2 Most state-of-the-art hearing aids are digital and adapt their settings automatically for best listening in various environments. This feature can be useful, especially for patients with dexterity issues, because it bypasses the need for manual hearing aid control. Additionally, the adaptive feature can make hearing aids more serviceable for patients with cognitive or memory issues. When selecting a hearing aid, assessment of these factors may be helpful. For example, those elderly patients that may experience reduced mobility, tactile sensitivity, and tremors may have exceptional difficulty changing the small hearing aid batteries; batteries generally need to be changed on a weekly basis. If batteries are left unchanged, the hearing aid itself is no longer of any use and will likely sit in the ear as an earplug rather than an assistive device. Additionally, visual issues that occur in the elderly population can further create a barrier in proper care for amplification devices. It is crucial to give a family member or caregiver the responsibility of caring for the device in terms of changing the batteries as well as general cleaning. Manual dexterity can be measured using the Nine-Hole Pegboard Test, which is designed to evaluate fine-motor coordination and finger dexterity.2 Visual-motor coordination and touch recognition may affect successful use of amplification and should also be evaluated.
Acclimatization
The concept of acclimatization must be discussed and addressed with the patient as part of the counseling. It is critical to allow ample time for auditory and cognitive acclimatization to hearing aids, especially in the case of overall auditory deprivation, or switching from a monaural to binaural array. Arlinger et al reported that acclimatization to hearing aids is associated with improvement in auditory performance over time, and acclimatization usually results in a 3 to 5% improvement in speech recognition ability.11 Factors impacting acclimatization include time course, age of patient, degree/configuration of hearing loss, previous experience, training effects, and the amount of audibility that it restores. Specifically, results have shown a significant acclimatization effect in a group of elderly individuals that were fitted monaurally with a linear algorithm.12 Although linear processing is less common in today’s hearing aid fittings, this further brings up the question of whether a monaural fitting is more appropriate in the elderly population.
Hearing Aid Arrangement: Monaural versus Binaural
In the case of bilateral hearing loss, choosing to invest in one versus two hearing aids is a decision that must be considered thoroughly. In general, binaural amplification is associated with increased speech understanding, improved directional hearing, improved spatial organization, and signal redundancy.13 Although many audiologists would consider binaural amplification to be the preferable option in the case of bilateral hearing loss, there is variable evidence regarding success in monaural versus binaural hearing aid fittings.12
It is accepted generally that a binaural fitting will provide the greatest localization and speech perception in both quiet and noise. Most studies indicate that binaural fittings help improve binaural squelch, head shadow effects, and binaural redundancy.14 Binaural amplification can also prevent auditory deprivation, a phenomenon described as a decrease over time in auditory performance associated with the reduced availability of acoustic information.11
In the case of elderly patients, however, this approach may not always be optimal. Contrary to these findings, other studies have suggested that binaural fittings can actually be more detrimental to the elderly user. In some cases, auditory processing disorders can present with binaural interference, making binaural speech perception worse than bestear abilities.15 Additionally, it has been found that elderly individuals often exhibit reduced speech intelligibility when aided binaurally as opposed to monaurally. This is referred to as the Binaural Interference Effect. Unless it is determined during the evaluation that the patient exhibits binaural interference, a binaural fitting should still be considered because the majority of patients will benefit from binaural amplification. Subjective reports or dichotic listening tasks are more helpful in determining this than typical audiometric speech tests, which have limited diagnostic value. It may take 6–12 weeks for an older adult to acclimate to binaural amplification, especially if one ear has been unaided for a lengthy period of time.2
Cox et al found that specific hearing loss parameters (severity, configuration) were not predictors of a monaural versus binaural preference.16 The investigators found that patients who preferred a monaural fit attributed this to comfort and quality. Patients who preferred a binaural fit attributed this to restoration of balance, clarity of sounds, and comfort. Nearly all hearing aid manufacturers and audiologists implement a trial period for hearing aids, allowing flexibility for the patient and audiologist to determine the fitting arrangement that provides the greatest benefit. Audiologists and otologists should remain alert for binaural interference in older patients and should not hesitate to recommend removal of one hearing aid if binaural amplification does not provide the expected result.
Hearing Aid Technology
Old hearing aid technology did very little to improve a person’s ability to understand but improved the ability to hear by making sounds louder. Recent hearing aid technology targets sensorineural losses with poorer discrimination, improving the amount of benefit individuals can receive from a hearing aid, although not necessarily truly improving discrimination ability. In addition to advances in technology, there is also a lot of flexibility regarding discretion. Many companies offer multiple color options so that the patient can choose if they want their hearing aid to match the tone of their skin or hair. Modern technology and color options have made hearing aids more appealing.
One of the most important things that a hearing aid does for people with hearing loss is it permits the individual to hear sounds with greater ease, reducing the strain of listening. Although the individual may not necessarily be able to understand more with an aid than without one, the device may relieve tension, fatigue, and some of the complications of a hearing impairment.
Over-the-Counter Hearing Aids
Amplification systems are often available over the counter at a considerably reduced price in comparison to those dispensed by a licensed professional. Although these may seem appealing due to their reduced cost and accessibility, these devices should be used with caution. This option may be beneficial for a select number of elderly patients that present with a relatively flat hearing loss and require only some additional gain for speech clarity. In this case, an over-the-counter amplification system may provide the needed benefit at a lower cost. Although a basic amplifier may work for a small percentage of elderly patients, they often do not take into account individual frequency and gain requirements and will often produce more distortion and discomfort rather than offering any noticeable benefit. Patients in these cases may end up wearing a device that is inappropriate for their audiological needs. For some, the poor performance experienced from these devices may deter them from trying other amplification altogether. Another unfortunate outcome may be that the patient often spends unnecessary costs before deciding to purchase devices from a licensed professional.
Body-Worn Hearing Aid
Given today’s microtechnology, the body aid is no longer dispensed. The body aid is a large, high-powered instrument worn on the body and connected to the ear via an earmold. Body aids offer a wide range of amplification and are often used by patients with severe to profound hearing impairment (Fig. 8.1). The microphone, amplifier, and battery are located in the case, which is worn on the body or carried in a pocket. The receiver is connected to the amplifiers by a long wire and is attached directly to the earmold—a custom earpiece designed to collect sound into the ear. This separation of receiver and microphone helps eliminate acoustical feedback in high-amplification instruments. Body aids can be fit to losses of 40 to 110 dBHL. Given that newer technology can also fit a wide range of hearing losses, body aids are now obsolete. Additionally, newer technology contains numerous digital feedback suppression algorithms, eliminating the issue of feedback for patients with significant amplification needs.
Behind-the-Ear (BTE)
Behind-the-ear (BTE) hearing aids are currently the best choice for severe to profound hearing losses. All of the necessary components of the amplifying system, including the battery, are held in a single case that sits behind the ear. The amplified sound is then fed to the ear via a plastic tube attached to a custom ear mold. This design provides adequate separation of microphone and receiver to reduce acoustical feedback, which can be common in severe losses. These hearing aids can be adapted for mild to profound losses, making them very flexible.
In-the-Ear (ITE)
Previously, in-the-ear (ITE) hearing aids (Fig. 8.2a) were the most widely dispensed. In these types of instruments, the entire hearing aid system is actually housed inside the earmold shell. The aids can help in various cases of hearing loss, typically anywhere in the range from 25 to 80 dBHL. Additionally, various modifications can be made to accommodate different degrees and configurations of hearing loss. There are several styles of ITE instruments available: full-shell (Fig. 8.2a); half-shell (Fig. 8.2b); in-the-canal (ITC) (Fig. 8.2c); and completely-in-the-canal (CIC) (Fig. 8.2b), listed from largest to smallest, respectively. One drawback of the smaller ITE styles is that they cannot adequately provide as much amplification as the larger shells, making them inappropriate for more severe hearing loss. Generally, the larger the device, the larger the fitting range. For those with dexterity and cognitive issues, a larger ITE style is often preferable for ease of insertion and manipulation. Also, the batteries tend to be larger in larger devices, therefore maintenance of batteries is easier, and battery life may be longer.
