There has been much cynicism regarding the value of hearing aids. However, a study published in JAMA confirmed what audiologists have recognized for decades: Hearing aids do indeed provide substantial benefit and reduce communication problems. The National Council on Aging study on the impact of untreated hearing loss in over 2000 hearing-impaired adults and their significant others indicated that individuals with untreated hearing loss were more likely to report depression, anxiety, and paranoia, and less likely to participate in organized social activities compared to those who wear hearing aids. Other studies have indicated that hearing aid use is associated with significant improvements in the social, psychological, emotional, and physical aspects of the lives of hearing-impaired persons with all degrees of hearing loss.

Despite these findings and data indicating significant improvements in satisfaction related to advanced technological features, the percentage of hearing-impaired individuals who own hearing aids has increased only slightly since 1984 and remains below 25%. Many individuals continue to reject hearing aid use for a combination of reasons, including denial of need, stigma, cost, and lack of adequate benefit in the more difficult, noisy listening environments in which help is most needed. In addition, patients are not likely to attempt to resolve problems they are not highly motivated to address without the expressed recommendation of their physician, yet less than 15% of adults receive hearing screenings from their medical doctor.

Types of Hearing Loss

Decades ago, it was believed that the use of hearing aids was limited to individuals with conductive hearing impairment and would not be helpful for individuals with a sensorineural hearing loss. Patients were informed that hearing aids could make sounds louder, but would not make them clearer. Currently, technologic improvements and improved fitting strategies allow for the successful fitting of hearing aids in most individuals with a sensorineural hearing impairment.

Degree of Hearing Loss

Hearing loss is too complex to be characterized by a single measure. Indeed, an audiogram provides information only about one aspect of hearing: threshold sensitivity. The reality is that individuals rarely listen at their hearing threshold. Instead, speech occurs at suprathreshold levels, and the intensity levels that an impaired cochlea is exposed to are considerably higher than normal because of amplification. For some patients, stimulation at high intensity levels enhances auditory function, but for others, it may not. Thus, the prognostic value of amplification and determination of candidacy for hearing aids on the basis of the degree of hearing loss is, at best, a questionable practice. If necessary, however, the following broad guidelines may be used (for a motivated individual).

Mild Hearing Loss (20–40 dB)

Hearing aid use may be helpful depending on the patient’s communicative needs. Some may prefer to use amplification only on a part-time basis.

Moderate Hearing Loss (45–65 dB)

Amplification is needed and is usually successful if proper fitting strategies are used.

Severe Hearing Loss (70–85 dB)

Amplification is necessary if the patient wishes to use the auditory channel as the primary receptive mode. Cochlear implants may be considered if hearing aids are unsuccessful.

Profound Hearing Loss (>85 dB)

At a minimum, amplification is useful as a warning device; at a maximum, it allows the patient auditory use and likely enhances speechreading capabilities. Its effectiveness may depend on the age at which amplification is first used. Individuals with a profound hearing loss may be strong candidates for cochlear implantation.

Audiometric Configuration

With the versatility available in digital hearing aids, audiometric configuration is not a significant issue in determining candidacy.

Word Recognition (Speech Discrimination)

In general, patients with good word recognition scores are more likely to do better with hearing aids. However, it would be a mistake to conclude that either success or failure would depend on this single factor. Word recognition assessed in a sound-treated test booth is not reflective of the variety of difficult listening environments that many hearing-impaired users encounter. Word recognition ability becomes diminished because of four main factors: (1) reduced audibility, (2) cochlear distortions producing reduced frequency and temporal selectivity and resolution, (3) abnormal central auditory processing, and (4) diminished cognitive function. Modern hearing aid technology allows the audiologist the ability to compensate for reduced audibility. The other three factors, however, may not be subject to correction by amplification; and may, in fact, render a poor prognosis for success with amplification. Furthermore, word recognition testing is typically performed in a quiet environment. It is well known that individuals with a sensorineural hearing loss have considerably more difficulty understanding speech in a noisy environment. This difficulty is often a function of both peripheral and central disorders and may be particularly emphasized in elderly populations.

Patients presenting bilateral significantly asymmetrical word recognition scores often prefer monaural amplification for the better hearing ear only. There are many exceptions; however, so unless there are other contraindications (eg, extremely poor speech discrimination ability, an extremely limited dynamic range, or medical contraindications), low discrimination scores should not, by themselves, preclude a trial with amplification.

Other Factors

It is not unusual to find that the most important factors determining the success or failure of hearing aids are those unrelated to audiometric findings. Specifically, one must take into consideration all of the following: (1) the age and general physical and mental health of the patient; (2) the patient’s, as opposed to only the family’s, motivation; (3) finances; (4) cosmetic considerations; and (5) communication needs.

Unfortunately, despite need, many patients resist trying hearing aids. There is an unfortunate, yet undeniable social stigma attached to wearing hearing aids. The issue of cosmetic vanity is nearly obsolete now because of the continuing trend toward miniaturization of hearing devices and the increased use of open coupler devices described and shown later in this chapter. However, not all hearing-impaired listeners are candidates for these hearing aids. It is regrettable that hearing aids are often dispensed to patients who lack motivation for amplification. A poorly motivated patient is a poor candidate for amplification regardless of the degree of hearing loss and should not be forced into trying hearing aids. It is difficult to undo the damage that may be done if a candidate prematurely tries and fails with amplification. For these patients, it may be advisable to provide them with information and to wait a while so that they may clearly perceive the need. However, encouraging patients to put forth the effort toward a trial period, with the understanding that it is possible they may be pleasantly surprised, is certainly worthwhile.

Occupational and social demands vary greatly among individuals. A judge who has a mild hearing loss may desperately need amplification, whereas a retired elderly patient with the same degree of hearing loss living alone may not. Patients must ask themselves if the ability to hear, albeit not understand, is acceptable and adequate for their needs. They must unselfishly examine whether they are becoming a burden to others, even if they do not personally recognize difficulty hearing. The critical variable is whether the patient experiences difficulty hearing or increased stress and fatigue in daily function. Amplification may simply relieve the strain of hearing, as opposed to improving word recognition or making sounds louder. This alone, however, can be a significant benefit. Thus, candidacy for amplification should be based on the patient’s subjective needs rather than strictly on the basis of the audiogram.

Over 80% of hearing aid fittings in the United States are binaural. A number of factors likely contribute to binaural superiority. Eliminating or minimizing the head shadow (the reduction in signal intensity from the side of the head opposite the signal) is important for listeners with a high-frequency hearing loss. Improved localization results from hearing sounds from both sides. A central release from masking (binaural squelch) may result in better hearing in noise. With binaural loudness summation, absolute binaural thresholds are 2–3 dB better than monaural thresholds. This summation effect occurs near threshold but not for high intensities near uncomfortable levels. Thus, the dynamic range of listening is greater for binaural listening than for monaural listening.

Other factors to consider in choosing binaural versus monaural amplification include the possibility of tinnitus reduction regardless of a perceived dominant side because of increased stimulation to more cortical neural substrate, and the legal implications of the potential deprivation of an unaided ear.

The general rule should be that unless there is a significant asymmetry in sensitivity, tolerance to loudness, or word recognition ability, or unless a medical condition exists contraindicating the insertion of anything into the external auditory meatus, the standard should be at least to try binaural amplification. For these patients, a wired or wireless contralateral routing of signal (CROS) aid or transcranial CROS (placing a hearing aid in the “dead” ear, producing bone conduction stimulation of the “good” ear) may be tried. It should be noted that CROS devices should be applied only if the better ear has normal or near-normal hearing, and the transcranial CROS should be used only if the poorer ear has no residual hearing that might produce recruitment or other distortion factors. If the “good” ear is in need of amplification, a bilateral contralateral routing of signal (BICROS), in which microphones are located on both ears but the signal is routed only to the “good” ear, can be tried. In cases of unilateral impairment, candidacy should be based on the individual’s communicative needs. It is also possible to try a bone-anchored hearing aid (BAHA) if the impaired ear is unaidable.