On the Definition of Hearing Handicap

Introduction

In 1976, the Executive Board of the American Speech-Language-Hearing Association (ASHA) passed a resolution recommending “that a Task Force on the Definition of Hearing Handicap be appointed to formulate and recommend to the Executive Board a definition of when a hearing impairment becomes a hearing handicap,” and this Task Force was formed in early 1978. In recent years, federal and state agencies, government program planners and regulators, third party payers, and a variety of special interests have looked to the American Speech-Language-Hearing Association for guidance and technical assistance on many matters pertaining to communicative disorders, including advice on such issues as (1) when should hearing-impaired persons be provided with rehabilitative assistance, (2) when should special services be provided to hearing-handicapped persons, (3) what constitutes a hearing handicap, and (4) when is a hearing handicap severe enough to warrant the payment of a disability award, financial assistance, or compensation for some injury or liability.

At times, the terms hearing impairment, hearing handicap, and hearing disability are used as if they are synonymous, when the terms should convey different meanings. In this report, these terms are defined in a manner similar to that advanced by the American Medical Association (1947, 1961, 1979). The term hearing impairment is used to mean a deviation or change for the worse in either auditory structure or auditory function, usually outside the range of normal. Hearing handicap means the disadvantage imposed by a hearing impairment on a person's communicative performance in the activities of daily living, and hearing disability means the determination of a financial award for the loss of function caused by any hearing impairment that results in significant hearing handicap.

Return to Top

Factors Contributing to Hearing Handicap

Defining the parameters of hearing handicap is a very complex task since impaired hearing is itself a very complex phenomenon. Persons with conductive hearing problems do not experience the same kinds of communicative problems or manifestations of auditory dysfunction presented by persons with sensorineural hearing loss, and the communicative problems and auditory manifestations presented by persons with peripheral hearing problems are not the same as those presented by others with central auditory dysfunction. The degree to which a hearing impairment is a handicapping condition will depend on the interaction of a number of factors, and ideally any definition of hearing handicap should be based on a comprehensive consideration of the interrelationship of such factors as:

• the present age of the individual,

• the age of the individual when the impairment developed,

• the age of the person when the impairment was first discovered,

• the nature and extent of the hearing impairment,

• the person's communicative needs and the nature of the settings in which communication occurs,

• the relationship of the hearing impairment to other physical or mental impairments,

• the amount and success of rehabilitative treatment already received,

• the individual's reaction and the reaction of others to his or her impaired hearing, and

• the effect of the hearing impairment on the individual's expressive communicative ability.

Specialists in communicative disorders deal with these variables in a clinical setting on a daily basis. They often are asked to provide expert judgments of the extent and nature of individuals' hearing impairments and hearing handicaps. Indeed, the determination of hearing handicap requires the judgment of qualified professionals who possess the requisite expert knowledge of human communication and its disorders. Ideally, decisions to grant compensation or some other financial award for hearing disability should be based on a sound professional judgment of the nature and degree of the handicapping condition. The size of a hearing disability award should be in direct proportion to the extent of the hearing handicap, and the method used for determining hearing handicap should be capable of discerning relatively small differences between handicapping conditions. Optimally, all of the factors that contribute to making the hearing impairment a handicapping condition should be discretely quantified and interrelated in an unambiguous manner, so that even a relatively untrained individual would he able to arrive at a reasonable determination of hearing disability. Unfortunately, no means currently exist to quantity and interrelate these factors in a way that would meet with widespread professional agreement.

The task of defining hearing handicap is awesome, since the definition should apply to a variety of circumstances, e.g., determining when a worker or accident victim deserves financial compensation for an acquired handicapping condition. Presently, no one definition of hearing handicap will adequately meet all the administrative or social program needs of hearing impaired persons. Rather, it is necessary to define hearing handicap in a variety of ways to address the particular needs of society's health, education and welfare programs. This report represents an attempt to address only one of those needs—a definition of hearing handicap useful in workers' compensation proceedings.

Return to Top

Hearing Handicap and Compensation

For many years, it has been recognized that engaging in certain noisy occupations for extended periods of time without adequate hearing protection can result in permanent changes in hearing function. Since the 1950s, the federal and state courts have maintained the liability of employers to compensate employees financially for hearing handicaps incurred as a result of job related conditions (Newby, 1964; Ginnold, 1974; McLauchlin, 1978; Ginnold, 1979). The orderly and equitable payment of compensation for hearing handicap requires a means for determining not only the existence but also the extent of hearing handicap. Over the years, a number of pure tone and speech audiometric methods have been used for making this determination, including:

• the Fletcher Point-Eight Rule which was derived from loudness and intelligibility data reported by Fletcher (1929) as a means for assessing hearing loss for speech;

• the 1942 American Medical Association (AMA) formula for estimating percentage of hearing loss on the basis of percent values ascribed to hearing threshold data at octave intervals between 256 and 4095 Hz (AMA, 1942);

• the Fowler-Sabine, or AMA, method which used a frequency-weighted average of hearing thresholds at 500, 1000, 2000, and 4000 Hz (AMA, 1947);

• the 1959 American Academy of Ophthalmology and Otolaryngology (AAOO) formula which used a simple average of hearing thresholds at 500, 1000, and 2000 Hz with a low fence and high fence cutoff for determining minimum and maximum impairment (AAOO, 1959);

• the Veterans Administration method (VA, 1976) and the Social Adequacy Index (Davis, 1948) which derived hearing handicap based on spondee thresholds and word discrimination test performance; and

• questionnaires or self-evaluation techniques (Nett, Doerfler, & Matthews, 1959; High, Fairbanks, & Glorig, 1964; Noble & Atherly, 1970; Alpiner, 1978; Noble, 1978; Giolas, Owens, Lamb, & Schubert, 1979).

Of all these methods, the formula advanced by the American Academy of Ophthalmology and Otolaryngology (AAOO) in 1959 has been used most widely as a basis for judicial and administrative determination of hearing disability. The AAOO formula has been used in 18 states as a means for determining workers' compensation awards, but has been criticized by the scientific community in recent years because (1) the formula's “low fence” for beginning handicap was too high and the “high fence” for establishing total handicap was too severe (Kryter, 1970, 1973; Noble, 1978; Suter, 1978a; Ginnold, 1979), and (2) the rule discounted the value of high-frequency hearing to understanding speech in everyday listening circumstances including noisy listening conditions (Kryter, Williams, & Green, 1962; Niemeyer, 1967; NIOSH, 1972; Kuzniarz, 1973; Anianson, 1974; Burns, 1977; Suter, 1978a; Ginnold, 1979). Consequently, some states—including California, New Jersey, and Wisconsin—have chosen not to use the 1959 AAOO formula for workers' compensation hearing disability claims because of one or more of the above criticisms. In 1969, the U.S. Department of Labor's Office of Workers' Compensation Programs (OWCP) abandoned the use of the 1959 AAOO method and adopted a variant of the formula which used high frequency threshold data for the determination of hearing disability (GAO, 1978).

Cognizant of the deficiencies that plagued the 1959 AAOO formula, the American Academy of Otolaryngology (AAO) recently revised its method for evaluating hearing handicap by incorporating hearing threshold data obtained at 3000 Hz as well as data from 500, 1000, and 2000 Hz (AMA, 1979). Percent hearing handicap for each ear is predicted by averaging hearing thresholds at the four frequencies, subtracting 25 from the average, and multiplying the result by 11/2.

Throughout the United States, the determination of the point at which a hearing impairment becomes a hearing handicap and the point at which that hearing handicap becomes a hearing disability is based on a variety of approaches (Ginnold, 1979). The lack of a generally accepted method for predicting hearing handicap has done little to assure that compensation awards granted under federal and state statutes are tempered by a meaningful reference to the degree of actual hearing handicap experienced by the individual. Discussions of methods for predicting hearing handicap at meetings of professional societies often turn into debates over the economic impact of one method or another on the financial awards granted to workers' compensation plaintiffs. Arguments of this type sap the vitality from the potential contributions those with expert knowledge might be able to render for society. How much an individual receives as compensation for his or her occupationally related hearing loss is a value judgment that is delegated to a society's duly constituted authorities who are charged with making administrative and judicial decisions about disability and should not be a factor confounding a professional's judgment about the extent of a hearing handicap.

Conversely, deciding how to define and describe when a hearing impairment becomes a hearing handicap is not a decision that should be left to administrators and lawyers. These are decisions that should be made by those with the requisite expertise in assessing human communication and its disorders. It is here where professional societies and their members can make a meaningful contribution to the social welfare by applying their professional talents in an appropriate manner. In this regard, then, the following sets forth a proposed procedure and a rationale for predicting degree of hearing handicap in a format that might be suitable as a basis for determining hearing disability for workers' compensation.

Return to Top

An Alternate Method for Predicting Hearing Handicap

As stated earlier, the point at which a hearing impairment becomes a hearing handicap will depend on several factors that go beyond a simple statement of the degree of hearing loss (i.e., an individual's age, onset of the problem, communicative need, etc.). Ideally, a method for describing degree of hearing handicap should be based on a comprehensive consideration of all these factors. To be useful as a means for determining hearing disability, however, the definition of hearing handicap should be straightforward and unambiguous, and hearing handicap judgments based on this definition should be consistent from one examiner to another. Unfortunately, there currently is no method of interrelating the variables that contribute to hearing handicap to produce uniformly consistent judgments regarding degree of hearing handicap across examiners.

There are many methods that can be used to assess hearing impairment; of them all, the methods for measuring pure tone auditory threshold sensitivity are very similar throughout the world. Tests of pure tone threshold sensitivity also can be administered using behavioral or electrophysiologic measurement techniques that can reduce the confounding influences of differences in listener sophistication or linguistic competence. On the other hand, there are no universally accepted or universally used measures of speech discrimination ability. While some speech discrimination measures, such as the CID Auditory Test W-22, enjoy more widespread use in the United States than others, no one measure of speech discrimination ability will meet the needs of all examiners for use with all hearing-impaired persons. Some speech discrimination tests require greater test taking sophistication, linguistic facility, and literacy from the listener than other tests. Additionally, methods for determining listener response reliability and accuracy in the presence of pseudohypoacusis are not well developed for speech discrimination measures. Response reliability and accuracy also can vary markedly when the materials used are not presented in the listener's native language.

Claims for workers' compensation are made primarily by persons with occupational histories of prolonged exposure to high levels of noise. Noise-induced damage to peripheral auditory structures can result in fairly predictable patterns of threshold sensitivity loss, but delineating a method for predicting hearing handicap solely on the basis of pure tone threshold data must be done with caution. Such an approach is reasonable only if those who use it are fully aware of its shortcomings.

Selection of Frequencies. Most everyday speech communication takes place under less than ideal listening circumstances (Pearson, 1976; Harris, 1965; Niemeyer, 1967; Kryter, 1973). Most human communication occurs in the presence of some degree of acoustic competition, and competing sounds will further degrade the intelligibility of speech received by hearing-impaired listeners. It is only reasonable to assume that any attempt to establish a relationship between pure tone sensitivity and speech discrimination ability should be done with speech discrimination data obtained under less than quiet listening conditions, since the objective of such a comparison is to determine when hearing impairment will disrupt communicative performance under conditions encountered in daily living.

A number of investigators have explored the relationship between threshold sensitivity and discrimination ability in quiet and in noise (Mullins & Ranks, 1957; Kryter, Williams, & Green, 1962; Ross, Huntington, Newby, & Dixon, 1965; Acton, 1970; Elkins, 1971; Lindeman, 1971; Anianson, 1974; Kuzniarz, 1973; Dickman, 1974) and have affirmed the importance of hearing sensitivity at 1000, 2000, 3000, and 4000 Hz for the discrimination of a variety of speech stimuli under quiet and noise listening conditions. Suter (1978a) noted that pure tone threshold data at 500, 1000, and 2000 Hz were the poorest predictors of speech discrimination ability in quiet or in noise; and when a variety of frequency combinations were examined, averaged threshold information at 1000, 2000 and 4000 Hz best predicted listener performance in noise. Suter concluded that any technique for assessing the ability of hearing-impaired individuals to understand speech in everyday listening conditions must include information regarding hearing above 2000 Hz.

Establishing the Low and High Fences. To be useful, any method used to describe the degree of hearing handicap on the basis of pure tone data (a) must define the threshold of beginning hearing handicap (the low fence), (b) must define the point at which a hearing impairment results in what must be considered a very severe or “complete” hearing handicap (the high fence), and (c) must provide a means for describing the degree of hearing handicap between these two extremes. Just as there are a variety of approaches for defining hearing handicap, there are almost as many approaches for describing or setting the low and high fences for hearing handicap.

For instance, in the Fletcher method, or the Point-Eight rule, the range of hearing for the average of hearing thresholds at 500, 1000, and 2000 Hz was divided into degrees of hearing loss from 0 dB to 120 dB SPL (Fletcher, 1929). In the Fowler-Sabine or AMA method (AMA, 1947) percentage hearing handicap values were determined by differentially weighting pure tone thresholds at 500, 1000, 2000, and 4000 Hz. A threshold for hearing handicap was established at 20 dB HL (ANSI, 1969) and a ceiling was set at 105 dB HL (ANSI, 1969). Hearing handicap is assessed by the Veterans Administration using spondee thresholds, monosyllabic speech discrimination scores, and pure tone thresholds at 250, 500, 1000, 2000, and 4000 Hz (VA, 1976). The veteran's hearing is considered normal if spondee thresholds are less than 26 dB HL (ANSI, 1969), if discrimination scores are above 92% in each ear, and if all pure tone thresholds between 250 and 4000 Hz are less than 40 dB HL and less than 25 dB HL for at least four frequencies. Maximum handicap is defined, generally, as when spondee thresholds exceed 96 dB HL regardless of speech discrimination ability or when speech discrimination ability is less than 40% regardless of spondee threshold level. In the 1959 AAOO method, no hearing handicap (i.e., the low fence) is said to exist when the average of hearing thresholds at 500, 1000, and 2000 Hz is 25 dB HL. (ANSI, 1969) or better. Complete hearing handicap (i.e., the high fence) is defined at an average of hearing thresholds at 500, 1000, and 2000 Hz of 92 dB HL (ANSI, 1969) or more.

There have been other approaches to defining low fence and high fence values, but they are basically only variations of the 1959 AAOO approach. For instance, in California the 25 dB low fence and the 92 dB high fence from the AAOO formula have been retained, but the frequencies used to calculate the frequency average are 500, 1000, 2000, and 3000 Hz instead of only 500, 1000, and 2000 Hz. This approach is identical to that which was adopted by the AMA in its most recent 1979 revision. Similarly, the U.S. Office of Workers' Compensation Programs also retained the 1959 AAOO low and high fence dB values, but calculated the hearing frequency average using threshold information at 1000, 2000, and 3000 Hz instead of 500, 1000, and 2000 Hz. The Committee on Hearing, Bioacoustics, and Biomechanism of the National Academy of Sciences (CHABA) has offered yet another alternate approach based on a simple average of hearing thresholds at 1000, 2000, and 3000 Hz by setting the low fence at 35 dB (CHABA, 1975). The purpose of CHABA's exercise, however, was to determine a low fence using 1000, 2000 and 3000 Hz that would result in no additional compensation than if a 25 dB low fence were used with an average of hearing thresholds at 500, 1000, and 2000 Hz.

Kryter (1973) has argued that the 1959 AAOO 25 dB low fence value was too high since it failed to account for when communication occurred in the presence of a background of noise. Kryter predicted that an individual with heating level at 25 dB for 500, 1000, and 2000 Hz would be able to repeat correctly only 90%, of sentence test items at a normal conversational intensity level. He argued that if hearing thresholds at 500, 1000, and 2000 Hz are to be used for determining degree of hearing handicap, then the low fence should be set at 15 dB HL (ANSI, 1969) and not at 25 dB HL. Similarly, Kryter felt that the 1959 AAOO high fence of 92 dB HL (ANSI) was unrealistic. He argued that the point at which most listeners would no longer be able to understand speech at everyday conversational levels was considerably lower than 92 dB. Kryter proposed setting the high fence at 75 dB when based on the average of hearing thresholds at 1000, 2000, and 3000 Hz.

Suter (1978a) compared her data on the performance of normal and hearing-impaired listeners on speech discrimination measures with data reported by Acton (1970). She noted that a 25 dB low fence was too high even when hearing thresholds were averaged at 1000, 2000, and 3000 Hz. She argued that when speech discrimination testing was performed in the presence of background noise, a low fence that would differentiate between handicapped and nonhandicapped persons would be more appropriate if set at 10 dB HL (ANSI, 1969) when averaging pure tone thresholds at 1000, 2000, and 3000 Hz and at 22 dB HL (ANSI, 1969) when averaging over thresholds at 1000, 2000, and 4000 Hz.

The low fence and high fence values used in any hearing handicap determination should be set in some reasonable relationship to the degree of communicative difficulty hearing-impaired individuals actually experience. The low fence should be set at a value above which it is reasonable to assume that hearing handicap exists, while the high fence should be set at a value above which it is reasonable to assume that the hearing handicap is complete. In this context, then, there is a reasonable certainty that a hearing-impaired adult would experience some degree of difficulty in discriminating everyday speech under everyday listening conditions when the average of hearing thresholds at 1000, 2000, 3000, and 4000 Hz is poorer than 25 dB HL (the low fence). Furthermore when an individual's average of hearing thresholds at 1000, 2000, 3000, and 4000 Hz exceeded 75 dB HL (the high fence), hearing handicap essentially can be considered complete, since conversation would be difficult to sustain for more than only short periods of time because a speaker would have to exert excessive vocal effort in order to communicate. Even at sustained intensity levels, the ability of such a severely hearing-impaired person to discriminate the high frequency acoustic cues necessary for the understanding of speech would be minimal.

Growth of Handicap. The simplest means for describing the growth of hearing handicap between these two extremes (i.e., 25 dB low fence and 75 dB high fence) is to assume a linear growth pattern of two percent for each dB increase in averaged hearing loss above 25 dB. While the actual growth in hearing handicap over this range may not be described perfectly by a linear function, using a nonlinear growth pattern for determining degree of hearing handicap would be cumbersome. In a subsequent analysis of her own data obtained from hearing-impaired listeners on speech discrimination tasks conducted in the presence of acoustic competition, Suter (1978b) reported that the relationship between listener speech discrimination performance and average listener hearing level at 1000, 2000, and 4000 Hz was described best by a linear function. Consequently, the assumption of a linear growth in hearing handicap over the range of average hearing levels at 1000, 2000, 3000, and 4000 Hz between 25 dB and 75 dB appears to be reasonable. Using a two percent linear growth rate simplifies even further the computation of predicted percent handicap compared to the one and one-half percent linear growth rate used in the AAOO (1959) and AMA (1979) formulae.

Unique Characteristic of This Alternate Approach. This approach for predicting hearing handicap differs from previous methods in that it discounts hearing loss greater than 75 dB when calculating the average amount of hearing loss across the four frequencies. For instance, if an individual's hearing threshold sensitivity at 1000, 2000, 3000, and 4000 Hz were 60 dB, 75 dB, 85 dB, and 90 dB, the figures used to calculate the average hearing loss across the four frequencies would be 60 dB, 75 dB, 75 dB, and 75 dB. A hearing loss of 75 dB effectively precludes an individual from hearing the higher frequency formats and format transitions essential to understanding everyday speech without the assistance of electronic amplification. The degree of handicap experienced by the unaided listener would be no more complete when thresholds at or above 1000 Hz exceeded 75 dB, and little is gained by accounting for the additional hearing loss above 75 dB when calculating the degree of hearing handicap.

Weighting the Importance of the Two Ears. Currently, there are no known data to support or refute the method used by the AMA for calculating percent predicted binaural handicap. Investigations should be encouraged to determine the validity of using specific better ear/poorer ear weighting procedures to determine binaural hearing handicap. In the meantime, a 5:1 better ear/poorer ear weighting applied to the calculation of binaural hearing handicap will suffice.

Return to Top

Summary

In this report the terms hearing impairment, hearing handicap, and hearing disability have been used to signify distinct ideas. Hearing impairment is defined as a deviation or change for the worse in either auditory structure or auditory function, usually outside the range of normal. Hearing handicap means the disadvantage imposed by a hearing impairment on a person's performance in the activities of daily living. Hearing disability means the determination of a financial award for the actual or presumed loss of ability to perform activities of daily living. Hearing impairment, particularly hearing sensitivity, is easily quantifiable, using procedures that are widely accepted within the professional community. Hearing handicap, however, is much more difficult to determine—so often hearing handicap is predicted on the basis of measures of hearing sensitivity. The problem with this predictive process is that many factors other than hearing sensitivity contribute to hearing handicap. While experimental efforts to quantify and interrelate these other contributing factors to hearing handicap should be encouraged in order to improve the accuracy of determining hearing handicap, the use of measures of hearing sensitivity as a means for determining hearing handicap should not be abandoned. In this report, a proposed method for determining degree of hearing handicap for workers' compensation purposes has been set forth. The method differs from others in that degree of hearing handicap is determined by:

• averaging hearing thresholds at 1000, 2000, 3000, and 4000 Hz;

• setting a low fence of 25 dB and a high fence of 75 dB;

• disregarding additional hearing sensitivity loss above 75 dB at the form frequencies used to calculate average hearing threshold level;

• assuming a 2%/dB linear growth of hearing handicap between the 25 dB low fence and the 75 dB high fence.