Impact of Hearing Loss on Daily Life and the Workplace
As people move through the activities of daily living at home, at work, and in social or business situations, basic auditory abilities take on functional significance. Audition makes it possible to detect and recognize meaningful environmental sounds, to identify the source and location of a sound, and, most importantly, to perceive and understand spoken language.
The ability of an individual to carry out auditory tasks in the real world is influenced not only by his or her hearing abilities, but also by a multitude of situational factors, such as background noise, competing signals, room acoustics, and familiarity with the situation. Such factors are important regardless of whether one has a hearing loss, but the effects are magnified when hearing is impaired. For example, when an individual with normal hearing engages in conversation in a quiet, well-lit setting, visual information from the speaker’s face, along with situational cues and linguistic context, can make communication quite effortless. In contrast, in a noisy environment, with poor lighting and limited visual cues, it may be much more difficult to carry on a conversation or to give and receive information. A person with hearing loss may be able to function very well in the former situation but may not be able to communicate at all in the latter.
In this chapter we examine what is known about the impact of hearing loss on adults as they function in daily life; the impact of hearing loss in the workplace; the effectiveness of sensory aids, prosthetic devices,
and assistive devices; and the implications and challenges for disability determination.
HEARING IN DAILY LIFE
Impact of Hearing Loss for Adults
Early Versus Late Onset
It is important at the outset to distinguish between adults who have experienced an early onset of severe or profound hearing loss and adults whose hearing loss was acquired later in life. When hearing loss occurs at an early age (i.e., prelingually, defined in this report as before age 2 years), there is an impact on the development of spoken language, on reading ability and educational attainment, and, ultimately, on employability (discussed further in Chapter 7). These persons are usually considered deaf, and a good number may use American Sign Language or a similar sign system as their preferred mode of communication. When hearing loss occurs after the development of spoken language, and particularly when it occurs slowly, as it does in aging or as the result of prolonged noise exposure, there is a loss of functional hearing ability, but other cognitive skills and competencies are not greatly affected. The terms “hard-of-hearing” and “late deafened” are often used to describe these individuals. In the sections that follow, we examine the impact of hearing loss in adults, with only occasional reference to etiology or time of onset. Nevertheless, each issue or research finding has greater relevance for one of these groups than for the other.
Education and Employment
Communication Access. Communication access for people with hearing loss can be described as “the right of deaf and hard of hearing people to receive and understand information and signals presented directly … and … the lack of barriers to, and the concomitant presence of access to, visual or auditory communication” (Barnartt, Seelman, and Gracer, 1990, p. 50). Individuals with hearing loss can perform as well as their counterparts without hearing loss when equitable educational and employment opportunities are provided (Schroedel and Geyer, 2000). These equitable opportunities are dependent on the individual student or worker having access to the information necessary for learning or for getting the job done. The nature of this communication access depends on individual needs and the auxiliary aids available to address these needs. For example, a deaf person who is unable to use the telephone can use a TTY or
computer system and can communicate with hearing peers through telephone or Internet relay systems. These systems provide operators who type or, via video, sign the hearing person’s spoken words for the deaf caller and voice the deaf person’s typed words or signed phrases for the hearing caller.
In the educational setting, an individual with a hearing loss is most likely to have trouble hearing what is said. In these situations, communication access is enhanced with the use of FM systems and other assistive listening devices (see Chapter 5), computer-assisted note-taking systems, and other accommodations. However, for various reasons, including background noise in the classroom, communication is often less than clear, thereby affecting access to the English language and educational achievement. Chapter 7 discusses hearing loss in an educational setting in greater detail.
Those with education are less likely to be in need of Social Security Disability Insurance and Supplemental Security Income (SSI) than those without education (Clarcq and Walter, 1997-1998). Most worrisome, however, is the 44 percent high school dropout rate among deaf students (Blanchfield, Feldman, Dunbar, and Gardner, 2001), compared with a general population rate of 19 percent. With high-stakes testing now being instituted by the states, the potential for this dropout rate to increase is high.
Buchanan (1999) notes that in addition to employer resistance to hiring deaf individuals, the automation of many work functions has disadvantaged the unskilled deaf worker. The implication here is that education is a critical factor that facilitates occupational entry and mobility for the deaf worker. The generally lower educational achievement of deaf persons continues to contribute to vocational difficulties. Those who lose their hearing later in life, and whose jobs depend on effective communication, run the risk of eventually losing their jobs if satisfactory accommodations, including the provision of auxiliary aids that meet their communication needs, are not instituted.
Americans with Disabilities Act. Title V of the Rehabilitation Act of 1973 was landmark legislation enacted to address job discrimination in federally supported programs that affected qualified people with disabilities (National Association of the Deaf, 2000). Under the Americans with Disabilities Act of 1990 (ADA), which was enacted in part because of pervasive ongoing discrimination in the mainstream of American public life, the removal of communication barriers (which deny information access for individuals with hearing loss equivalent to what hearing persons might have) became a legal right for deaf and hard-of-hearing people (National Association of the Deaf, 2000). The legal protection of both acts
covers individuals who can demonstrate that, even with corrective devices such as hearing aids or cochlear implants, they have a substantial impairment to a major life activity—for example, the inability to distinguish words due to background noise on the job. Public venues must provide auxiliary aids or services when necessary. A comprehensive list of auxiliary aids and services required by the ADA is included in the corresponding regulations, with the understanding that evolving technology will create new devices.
Psychosocial Impact of Hearing Loss
Perspectives of the Deaf Community
The deaf community is defined as an entity that shares the common goals of its members and works toward these goals (Padden, 1980). These goals include, for example, telecommunications and entertainment access, captioning, sign language and oral interpreting, and accommodations in the work setting. For the most part, the deaf community comprises individuals who have been deaf from birth or early in life (Lane, Hoffmeister, and Bahan, 1996). Some of these individuals prefer oral communication but see themselves as part of the deaf community. Most are deaf individuals who rely on some form of signed communication or American Sign Language and identify with Deaf Culture. These individuals value American Sign Language as their language, and they tend to devalue speech when they interact with each other. Socialization with other deaf persons is strongly emphasized, particularly through local, state, and national associations, sports leagues, deaf clubs, religious settings, and Deaf festivals (Lane et al., 1996; Padden and Humphries, 1988).
Within the deaf community, hearing loss is not a detriment to socialization; rather, it brings people with common issues together into a vibrant entity (Andrews, Leigh, and Weiner, 2004). As Lane, Hoffmeister, and Bahan (1996) indicate, hearing loss as measured in decibels is not a significant issue for those who identify with Deaf Culture as defined above. Rather, what is significant is how deaf community members relate to each other and how they communicate with each other. The use of vision rather than audition to communicate, most often using sign language, is integral to their daily living (Andrews et al., 2004). Many wear hearing aids to alert them to environmental noises at the very least, but audition is still not primary in their lives. While some value their previous speech and auditory therapy to maximize spoken English abilities, others may experience such exposure as stressful and potentially inadequate in providing them with functional expressive and receptive spoken English skills (Bain, Scott, and Steinberg, 2004). It must be kept in mind that most
individuals whose hearing loss goes back to the early years of life do have the ability to speak with varying degrees of clarity ranging from speech indistinguishable from hearing peers to speech that is incomprehensible, depending not necessarily on level of hearing loss, but rather on background training, ability to benefit from hearing devices, and the use of speech (Blamey, 2003).
Generally, those identifying with Deaf Culture see sign language as providing them with critical access to language, communication, and positive social experiences. Because they have a language acquired through vision and a means to education, they do not see themselves as disabled per se, although many will acknowledge having a disability regarding the lack of hearing that entitles them to coverage under the ADA and its provisions for more equal opportunities. Hearing disability per se is not as much an issue for them as is the disability engendered by society’s reluctance to accommodate to their needs by providing interpreter services, captioning, and other means of access to communication (Lane et al., 1996). This reluctance of society is what they see as profoundly disabling.
Psychosocial Adjustment and Hearing Loss
The majority of those with hearing loss acquire it later in life at a time following the acquisition of spoken language. The prevalence is particularly high among those who are over 65 years of age and among those who have been exposed to noise. Because hearing loss tends to disrupt interpersonal communication and to interfere with perception of meaningful environmental sounds, some individuals experience significant levels of distress as a result of their hearing problems. For example, some express embarrassment and self-criticism when they have difficulty understanding others or when they make perceptual errors. Others have difficulty accepting their hearing loss and are unwilling to admit their hearing problems to others. Anger and frustration can occur when communication problems arise, and many individuals experience discouragement, guilt, and stress related to their hearing loss. These negative reactions are also associated with reports of negative attitudes and uncooperative behaviors of others (Demorest and Erdman, 1989).
Interestingly, the association between degree of hearing loss and psychosocial adjustment to hearing loss per se is not strong (Erdman and Demorest, 1998). Individuals with virtually identical audiograms and clinical test results may differ greatly in their self-reported adjustment problems. This finding is not unique to the impact of hearing loss on psychosocial adjustment; low (negative) correlations between severity of impairment and degree of psychosocial adjustment have been found re-
peatedly in the disability literature for a wide variety of health-related problems (Shontz, 1971).
Given the high variability in how individuals adjust to their hearing problems, it is not surprising that hearing loss does not seem to affect basic personality structure (Thomas, 1984). Although many adults are resilient, acquired hearing difficulties are nevertheless responsible for a high level of general psychological distress for a significant number of people due in part to isolation, loneliness, and withdrawal (Meadow-Orlans, 1985). This distress, which may be manifested in heightened anxiety, depression, sleep disturbance, and the like, is observed not only among those who seek audiological evaluation, but also among those reluctant to acknowledge a hearing problem (Hallberg and Barrenas, 1995; Hetu, Riverin, Getty, Lalande, and St-Cyr, 1990; Hetu, Riverin, Lalande, Getty, and St-Cyr, 1988) and among those who have already acquired hearing aids (Thomas, 1984, 1988). This psychological distress can significantly impact the family or significant others as well as the individual (Schein, Bottum, Lawler, Madory, and Wantuch, 2001).
Similarly to what has been found for psychosocial adjustment, studies to date have consistently demonstrated that there is no overall association between hearing loss and psychopathology. Rosen (1979) has confirmed this for individuals with acquired hearing loss, and Pollard (1994) has confirmed it from an analysis of public mental health records on deaf and hard-of-hearing individuals in the Rochester, New York, vicinity. Despite this lack of association, it is important to acknowledge that psychological distress can be a factor in adjustment difficulties.
Knutson et al. (1998) have investigated whether the use of cochlear implants can affect the social adjustment of those with acquired hearing loss. In a study of psychological change over 54 months of cochlear implant use by 37 postlingually deafened adults, the researchers used standard psychological measures of affect, social function, and personality prior to implantation, and then at regularly scheduled intervals after implantation, to assess the impact of audiological benefit. There was evidence of significant improvement on measures of loneliness, social anxiety, paranoia, social introversion, and distress. To a lesser extent, improvement was also noted for depression. Improvement of marital distress and assertiveness took comparatively longer to emerge. One caveat is that because of the complexities of individual life issues and personality attributes, it is not possible to attribute the improvement in psychological measures solely to the influence of audiological benefits. How well the improvement noted on self-report measures translates into actual social and job situations has not been determined.
Hearing in the Workplace
Prevalence of Hearing Loss in the Workplace
Although there have been numerous surveys used to estimate the prevalence of hearing loss in the general population, there is no comparable survey of prevalence in the workplace. Prevalence rates in the general population, broken down with respect to age and gender, can be used, with appropriate weights, to derive such estimates. For example, according to a survey of 80,000 households in the National Family Opinion (NFO) panel conducted in November 2000, 275 per 1,000 households reported having a person with a hearing difficulty, in one or both ears, without the use of hearing aid (Kochkin, 2001). The NFO panel is balanced to reflect U.S. census information, and the survey results translate to an estimated 28.6 million households reporting hearing loss.1 Although the age distribution reported by Kochkin leads to an estimate of 17.4 million adults of working age (18-64) in the United States, it is very difficult to estimate the numbers actually in the workplace. The disabling outcomes of hearing loss are likely to reduce this number, but as discussed by Mital (1994), the median age of the population is increasing and many older workers are delaying retirement for financial reasons, thereby increasing the numbers of older adults in the workplace.2
Despite our inability to derive an estimate of the number of individuals with hearing loss in the workplace, it is clear that many such individuals function, and function quite well, despite their impairment. As noted in Chapter 1, a great many factors influence employability and performance, and these must be taken into account when accurate prediction of disability for an individual is needed.
Employment Status of Adults with Hearing Loss
Educational level is a key factor in understanding the employment status of adults with hearing loss. For those individuals with early onset of hearing loss, the challenges for acquisition of spoken language, devel-
Although the sampling unit for this estimate is the household, the estimate is often reported and interpreted as the number of individuals with hearing loss. Because a given household can have more than one individual with hearing loss, 28.6 million is probably an underestimate of the prevalence of hearing loss in the population that was sampled. Current estimates (see Chapter 1) are closer to 34 million individuals.
A recent report (National Research Council, 2004) from the National Academies, Health and Safety Needs of Older Workers, may be of interest to readers concerned with the aging workforce and its special needs.
opment of reading skills, and educational achievement result in limited job opportunities. These problems, combined with needs for better career guidance, job training, and job placement, result in poor preparation for entering the workforce on a competitive basis (Phillippe and Auvenshine, 1985).
Positive career outcomes are statistically related to educational level, although this relationship does not imply a causal linkage. Clarcq and Walter (1997-1998) compared graduates of high schools for the deaf ages 28-32 with individuals who had attended or graduated from the postsecondary National Technical Institute for the Deaf (NTID). They found that 33 percent of the high school graduates were receiving SSI benefits compared with 12 percent of those with some college education and 0 percent of those who had graduated from NTID. Schroedel and Geyer (2000) examined the long-term career attainments of deaf and hard-of-hearing college graduates and found that most were successfully employed and satisfied with life. Many had completed graduate degrees and were employed in white-collar positions.3 Similarly, Welsh (1993) examined factors affecting the career mobility of deaf adults and recommended that they pursue the highest degree of education possible and that they target careers in which the demand for workers is greatest.
When hearing loss occurs during adulthood, after the completion of formal education and after establishment of a work history or career, it poses challenges for job performance and future job mobility. Because these adults have already acquired the knowledge and skills needed to perform their jobs, the difficulties they face are related to communication barriers, such as working conditions and employer attitudes, as discussed in the following sections.
For an individual with hearing impairment, the most obvious communication problem in the workplace is the presence of background noise. Noise is highly prevalent in industrial settings and, among workers with noise-induced hearing loss, noise is mentioned most frequently as an obstacle and a source of annoyance in the workplace (Hetu, 1994; Laroche,
Garcia, and Barrette, 2000). Other surveys and focus groups of workers with hearing loss have highlighted physical aspects of the work environment, the need to use telephones or videoconferencing, the difficulty of group communication situations, and difficulties presented by various speaker characteristics (Laroche et al., 2000; Scherich and Mowry, 1997).
Employer attitudes are another barrier. According to the National Association of the Deaf, “employer attitudes create the largest single barrier to employment opportunities” (National Association of the Deaf, 2000, p. 123). Schroedel and Geyer (2000) cite studies indicating that communication stress, social isolation, and unsupportive supervisors are among the difficulties encountered by many deaf and hard-of-hearing workers. Of concerns expressed by employers of adults with hearing loss, 62 percent were communication-related and 24 percent were safety-related (Dowler and Walls, 1996). When these concerns are addressed, employer satisfaction tends to increase (Dowler and Walls, 1996).
Effectiveness of Sensory Aids, Prostheses, and Assistive Devices
As described in Chapter 5, there are a great many devices available today that can restore some of the function that is lost as a result of hearing impairment. However, most studies of the potential effectiveness of these devices are based on laboratory or clinical research, not on assessment of actual functioning in the workplace.
For persons with severe or profound hearing loss, the literature on cochlear implants provides data showing significant restoration of function for many implant recipients. Studies have confirmed, however, that individuals with lifelong profound deafness who undergo cochlear implantation do not do as well with speech recognition as individuals with late-onset hearing loss (e.g., Dorman, 1998), primarily because of limited exposure to auditory experiences and limited understanding of what auditory stimuli mean. Nonetheless, an increasing number of these adults with strong ties to the deaf community are considering cochlear implants in order to gain access to the world of sound (Christiansen and Leigh, 2002). For the most part, these individuals desire to maintain contact with the deaf community and do not necessarily reject the values of Deaf Culture. The level of hearing loss is important only insofar as it qualifies them to become candidates for the surgery, if they are so inclined. After implantation, rarely do they pick up skills such as using telephones effectively or understanding speakers in groups and in other listening situations.
ADA and Accommodation
Although the ADA has mandated accommodations in the workplace, and there are devices and other methods of accommodation that can reduce or eliminate disability for those with hearing loss, there is evidence that such accommodations are underutilized. According to results of a series of focus groups with over 100 members of Self Help for Hard of Hearing People (SHHH) (Stika, 1997), several factors account for this. Lack of knowledge on the part of both employees and employers concerning what is available and what is required by the ADA is one factor. Perhaps more pervasive, however, are apprehension, concern, and anxiety about the consequences of making one’s hearing loss known to others (Glass and Elliott, 1993; Stika, 1997). Workers with hearing loss report high levels of psychological stress associated with fears of appearing (or being) incompetent, feelings of self-consciousness, overcompensation, and lowered self-esteem. Indeed, Hétu and his colleagues (Hetu, Getty, and Waridel, 1994) found that fears of stigmatization due to hearing loss are not without foundation. Mark Ross (1994, p. xii) states that “the greatest challenge we face regarding communication access is neither technological nor legislative, but societal attitudes toward hearing loss—attitudes that seem to be shared fully by many people with hearing losses.” These findings point to the need for education and intervention both with the individual with hearing loss and with his or her coworkers and supervisors.
As discussed in Chapter 1, the term “disability” has been defined in different ways over time, and this is quite apparent in the differing approaches to disability found today. The earlier conceptualization, based on a medical model, viewed disability as a direct consequence of impairment and therefore measurement of impairment could be used, with suitable medical criteria, for disability determination. This approach is embodied in the medical listings used by the Social Security Administration (SSA) to determine that an individual is unable to work.
In contrast, the approach taken by the World Health Organization, and embodied in the ADA, is based on a social model of disability. This approach is a more positive one, in which the emphasis is on what an individual with an impairment can do, and the capabilities the person does have. The new emphasis is on accommodation and restructuring of the environment so as to maximize each individual’s functioning in daily life.
These differing perspectives on disability create challenges and apparent inconsistencies in disability determination. For example, is it reasonable for deaf adults to claim on one hand that they are disabled and hence entitled to accommodations at work, while at the same time arguing forcefully that hearing loss is not a disability and that the only thing a deaf person cannot do is to hear? In the sections that follow, disability assessment is discussed from a measurement perspective, and elements of both of these approaches are apparent. In agreement with the social model, however, we note that disability is usually not absolute, and that as conditions change and accommodations are made available (and accessed), disability may be reversed.
In previous chapters the nature of hearing loss and its impact on auditory function was described in terms of clinical tests that have proven diagnostic value or that are assumed to assess auditory skills that are important in daily life. Conspicuously lacking, however, are empirical studies establishing the link between the clinical measures and performance in natural settings. In their review of the literature on sound localization, Middlebrooks and Green (1991) note that laboratory studies are designed to isolate the effects of one particular variable, with the effects of other factors controlled and held constant. In daily life, these factors are free to vary and to interact, and hence generalization from the laboratory to the real world cannot readily be made. As they state: “there is often no evidence to indicate the importance of that cue in a more realistic setting” (p. 136).
As discussed in Chapter 1, the social model of disability implies that disability, as an outcome, is a function not only of the individual’s hearing loss, but also of other factors internal and external to the individual. This highlights the dilemma posed by trying to predict the consequences of hearing loss that occur in daily life: the farther one moves from testing the ear per se, the more meaningful the measure may be, but the less it is a function of hearing ability alone. This implies that impairment in a specific auditory ability may not be strongly correlated with disability, and indeed this has been shown to be true for the relation between degree of hearing loss measured audiometrically and self-reported communication function in daily life. Correlations are high enough to support the assumption of a causal link between impairment and disability (as well as the validity of the self-reports), but low enough to preclude accurate prediction of disability for individuals from the auditory measures alone.
In principle, it is possible to develop clinical tests with acceptable predictive validity, but in practice it will likely require testing conditions
that are more representative of how the person functions in the real world. Some of the issues that would need to be considered are binaural versus monaural hearing, free field testing versus testing using headphones, testing with more complex stimulus materials (such as real-world sounds and sentences, connected discourse, or competing noise), and the role of visual information and auditory-visual integration, to name just a few.
The challenge of validating clinical tests in terms of performance in daily life is magnified by the complexity of real-world auditory environments and by the fact that clinical tests differ from those that are needed for functional assessment. A model for the functional approach (Laroche et al., 2003) illustrates the complexity of identifying hearing requirements and noise environments in specific jobs. Laroche et al. used the Hearing in Noise Test (Nilsson, Soli, and Sullivan, 1994) to screen for functional hearing. First, hearing-critical tasks and locations in the workplace (the Canadian Coast Guard and the conservation and protection departments of Fisheries and Oceans Canada) were identified, and performance parameters for those tasks (e.g., accuracy level, distance) were determined. Noise recordings were made in those environments, simulated in the laboratory, and used with normal-hearing listeners to develop a screening test. Statistical modeling was used to derive performance tables, and the listening tests were then validated on listeners with hearing loss. In the final stage, minimal acceptable performance criteria were established and screening scores were determined. This comprehensive and systematic approach, integrating theoretical and statistical models, psychometric instrument evaluation, and empirical determination of workplace characteristics, clearly illustrates the challenges involved in direct assessment of functional hearing abilities.
Many forms of assessment can be considered indirect; that is, they do not involve direct observation of target behaviors. One way, discussed in previous chapters, is the use of a measurement on one variable (such as a clinical test of pure-tone thresholds) to predict or estimate performance on a different target variable (such as speech communication at work). A strong relation between the predictor and the target validates the use of the predictor in place of direct measurement of the target.
Another type of indirect assessment occurs when a self-report or self-assessment is used in lieu of direct behavioral observation. This method has been used extensively in audiology to obtain information about communication problems and communication strategies that could, in principle, be measured by direct observation. Interestingly, such instruments have also been used to obtain direct measures of the respondent’s atti-
tudes, beliefs, feelings, and reactions to experiences in everyday life. These cognitive and affective variables are not directly observable and, as a result, they are usually measured using self-reports.
A third type of indirect assessment may be termed doubly indirect. This occurs when a self-report on one variable, or a difference between two such reports, is used as a measure of another variable. For example, self-reported communication with a hearing aid (an indirect measure of aided communication) might be interpreted as measure of “health-related quality of life” (another variable), or a change in self-reported communication problems after receiving a cochlear implant (a difference between two indirect measures of communication) might be used as a measure of “benefit from the implant” (another variable). These measures are quite different from asking the individual to report on quality of life per se or using behavioral measures of performance to evaluate benefit from the cochlear implant. Doubly indirect assessment compounds the difficulties in arriving at valid conclusions because of the many additional assumptions that must be made about the relation between the target variable and the one actually assessed. In the sections that follow, examples of all three types of indirect assessment can be found.
Assessment of Hearing Disability, Handicap, and Benefit from Interventions
Efforts to assess hearing handicap and disability through self-report questionnaires have been ongoing since publication of the Hearing Handicap Scale by High, Fairbanks, and Glorig (1964) and the Hearing Measurement Scale (Noble and Atherley, 1970). The essential role of self-report in assessment of disability and handicap and the unique perspective of the affected individual are widely acknowledged and now generally accepted (Baldwin, 2000; Dobie and Sakai, 2001).
The earliest scales focused on self-reported abilities and difficulties experienced by the hearing-impaired individual in daily life. The use of terminology has been inconsistent, however, and the targeted constructs suggested by an instrument’s name have not always been consistent with the content of its questions or items. The Hearing Handicap Scale, for example, contains items dealing primarily with detection of sounds and understanding of speech—functions that today are considered aspects of hearing disability. Similarly, early surveys of hearing aid users did not adequately distinguish among hearing aid use, hearing aid benefit, and satisfaction with a hearing aid. Attention to psychometric principles in the development, evaluation, and application of self-assessment tools has been strongly advocated (e.g., Demorest and Walden, 1984; Hyde, 2000), and surveys and recent critical reviews of self-assessment instruments
(e.g., Bentler and Kramer, 2000; Demorest and DeHaven, 1993; Noble, 1998) have generally been positive.
As sophistication in instrument design has increased, so has the conceptualization of the constructs to be measured. The most dramatic changes have occurred in the assessment of hearing aid outcomes, as documented by a collection of eight articles devoted to that topic in two issues of the 1999 volume of the Journal of the American Academy of Audiology (Cox, 1999a, 1999b). Distinctions between objective and subjective outcomes, and conceptual distinctions among hearing aid benefit, satisfaction, and use, along with statistical analysis of their interrelationships, have led to the conclusion that hearing aid outcomes are truly multidi-mensional (Humes, 1999). Another important development has been the recognition that standardized assessments, in which the same questions are asked of all respondents, can fail to assess areas of function that are important to the individual. Examples of personalized assessments are the Client Oriented Scale of Improvement (COSI) (Dillon, Birtles, and Lovegrove, 1999) and the Glasgow Hearing Aid Benefit Profile (GHABP) (Gatehouse, 1999).
Quality of Life. Among the most popular approaches to outcomes assessment has been the attempt to measure a global outcome called “quality of life.” Quality of life is a concept that encompasses physical, social, psychological, and environmental aspects of an individual’s life. In the social and medical sciences, the concept has defied precise and distinct conceptualization (Rogerson, 1995), and operational definitions range from health economists’ quality-adjusted life years (QALY) to scores on disease-specific self-report questionnaires. In Rogerson’s conceptualization, environmental and health-related quality of life are each viewed as a sense of satisfaction and well-being that is multiply determined: by external factors and their characteristics and by the characteristics of the individuals themselves. Palmore and Luikart (1972), Flanagan (1978), and Bowling (1995) have taken an empirical approach to determining what is most important to adults in the general population. Their studies revealed similar factors, with health (both one’s own and that of significant others) high on the list and physical welfare/finances/standard of living also in the top five. Bowling reported that “relationships with family and relatives” was the most frequently mentioned and most frequently first-ranked item.
Health-Related Quality of Life. Given the impact of hearing loss on communication and interpersonal functioning and the importance of interpersonal relationships in determining quality of life, it is not surprising that there has been significant interest in incorporating health-related quality-
of-life measures into the diagnosis of rehabilitative needs of persons with hearing loss and the evaluation of rehabilitative interventions. In a causal chain that begins with hearing loss and its effects on disability and handicap (World Health Organization, 1980), quality of life is an ultimate state or outcome that is a function of all three (Ebrahim, 1995). As might be expected, issues of conceptualization and operational definition have been no less difficult in audiology than in other behavioral domains.
Global measures of health-related quality of life (HRQL) serve several purposes, both at a population level and at an individual level. Clinically, they may be useful in diagnosis of disease, assessment of prognosis, treatment outcome evaluation, and determination of etiology (Ebrahim, 1995). Examples of global HRQL instruments include the Self Evaluation of Life Function (SELF) scale (Linn and Linn, 1984), the Sickness Impact Profile (Bregner, Bobbitt, Carter, and Gilson, 1981), the EuroQOL (The EuroQol Group, 1990), the Medical Outcomes Study Short Form 36 (SF-36) (Ware and Sherbourne, 1992), the World Health Organization’s WHOQOL (1993), and the Dartmouth COOP Functional Health Assessment (Nelson, Wasson, Johnson, and Hays, 1996).
There is evidence of an association between some global quality-of-life scales and degree of hearing loss. Bess, Lichtenstein, Logan, Burger, and Nelson (1989) found a systematic relation between degree of hearing impairment and scores on the physical, psychosocial, and overall scales of the Sickness Impact Profile. Similarly, Dalton et al. (2003) have reported that hearing loss, self-reported hearing handicap, and communication difficulties were associated with small but significant differences in quality of life, as measured by the SF-36.
Despite the attractiveness of having such global measures, their usefulness has been questioned on conceptual and psychometric grounds (Ebrahim, 1995), and they have not been found to be sufficiently sensitive to detect clinically meaningful changes in adults with hearing loss. Bess (2000) reviewed studies that used the Sickness Impact Profile, the SELF, the SF-36, and the Dartmouth COOP Functional Health Assessment to evaluate the outcomes of hearing-aid fitting, often in conjunction with more communication-specific assessments. The benefits of amplification were typically found on the latter measures but not on the more general quality-of-life measures. This lack of sensitivity is understandable, given the myriad factors that influence outcomes far removed from the causal agents one wishes to evaluate. Perhaps for this reason, Ebrahim concludes that measures of impairment, disability, and handicap have advantages over global health-related quality-of-life measures for clinical purposes. Disease-specific instruments that are grounded in an understanding of predictable disease consequences and precise treatment outcome goals afford greater potential, ipso facto, of being sensitive to treatment effects.
Appropriate Uses of Self-Assessment Instruments
Self-assessment scales have been used widely in research and in clinical settings. Scales focusing on disability and handicap have been used successfully to evaluate the need for audiological rehabilitation and to measure the outcomes of treatment interventions, such as hearing aids, cochlear implants, and specific rehabilitation programs. Such uses are appropriate when there is psychometric evidence of the tests’ validity for these purposes. However, despite the considerable progress that has been made in the conceptualization and assessment of hearing disability and handicap (as defined by the World Health Organization), these measurements have little to offer in disability determination as defined by SSA. When a client seeks treatment for a hearing loss, it is usually assumed that symptoms are reported conscientiously. In contrast, when assessment is conducted for purposes of determining compensation, there is an inherent conflict of interest, and self-reports cannot be used with confidence (Dobie, 1996).
What, then, is the role of self-assessed disability or handicap in a compensation context? Dobie and Sakai (2001) argue that direct measurement of disability and handicap through self-report constitutes a gold standard, but that surrogate measures must be used in contexts in which compensation is involved. Despite the fact that audiometric measures of pure-tone threshold and speech recognition are imperfectly correlated with disability/handicap, they argue that these (more objective) measures can serve as surrogates in a compensation context. Moreover, based on the available data, they find insufficient evidence to support a change from the 1979 AAO-HNS/AMA (American Medical Association, 2001) method of estimating hearing handicap. Research is needed to more fully understand the relations and interactions among objective measures of hearing abilities, demographic and psychological factors, and self-reported communication outcomes and to evaluate the unique contribution of hearing loss among these other influences.
The committee examined the use of self-reports and concludes that self-reports should not be used as criteria for disability determination. In clinical settings, there is little motivation for exaggeration of problems, but in the context of disability determination, conflict of interest poses a serious threat to the validity of self-reports.
The committee examined the potential usefulness of quality of life as
an outcome variable. First, because quality of life is assessed through self-report, the conflict of interest that arises with all self-reports in disability determination applies equally to measures of quality of life. In addition, the committee concludes that definitions of quality of life, including health-related quality of life, are not sufficiently precise for such assessments to provide useful outcome measures. Finally, the labeling of hearing-related self-assessments as measures of quality of life is to be discouraged, as it is a doubly indirect form of assessment.
Self-reports can provide valuable, albeit indirect, information about an individual’s functioning in daily life. For this reason, they can and should be used as outcome measures in predictive validation studies that do not involve claimants.
Tests that purport to measure or predict functional hearing ability in daily life must be validated against real-world criteria measured in natural settings. Validation in a simulated test environment is appropriate if a strong relation between the simulated and naturalistic settings can be demonstrated or assumed.
Research Recommendation 6-1. Research is needed on the prevalence of hearing loss in the workplace and on its effects on worker performance. In conjunction with this, the effectiveness of workplace accommodations, including devices and other types of accommodation, needs to be established.