Fitness for Duty
Jennifer Tufts, Ph.D., CCC-A, University of Connecticut
The virtuoso violinist and the firefighter spend their working days very differently – but each must be able to hear in order to do his or her job well. In the case of the virtuoso violinist, an inability to hear could mean the end of a career. In the case of the firefighter, an inability to hear could mean the difference between life and death. But how good does hearing need to be in these and other hearing-critical occupations, such as law enforcement and piloting? The answer is surprisingly elusive.
Auditory fitness for duty (AFFD) refers to the possession of hearing abilities sufficient for safe and effective job performance. AFFD is evaluated as a condition of employment in occupations that are physically hazardous or that involve the safety of others (e.g., the firefighter or the pilot, but not the violinist). AFFD standards for the U.S. military are established by the Department of Defense (Department of Defense, 2005). For federal civilian jobs, the Office of Personnel Management establishes AFFD standards (LaCroix, 1996a). State agencies, and even private companies, may adopt federal AFFD protocols or establish their own standards. Most guidelines require AFFD evaluations to be conducted by a supervised audiometric technician, an occupational hearing conservationist certified by the Council for Accreditation of Occupational Hearing Conservationists, or a licensed and/or certified audiologist.
Assessing AFFD usually involves, at the very least, obtaining pure-tone air conduction thresholds at 500, 1000, and 2000 Hz. Pass/ fail cut-off values at these frequencies generally fall between 20 and 35 dB HL. Testing at some combination of 3000, 4000, and/or 6000 Hz is usually required as well. The pass/fail cut-off values at these frequencies tend to be somewhat higher. Protocols vary as to whether pass/fail criteria are identical for each ear, or whether a certain degree of asymmetry between ears is acceptable.
As an example, the audiometric requirements for enlistment into the U.S. Armed Forces are the following: thresholds in either ear no greater than 35 dB HL at 500, 1000, and 2000 Hz, with the average of these frequencies in each ear no greater than 30 dB HL; and thresholds at 3000 and 4000 Hz no greater than 45 and 55 dB HL, respectively, in either ear (Department of Defense, 2005). Individuals with bilateral mild-to-moderate hearing loss are not excluded from enlistment. In fact, almost all AFFD protocols allow some degree of hearing loss (i.e., thresholds >20 dB HL). This is partly an historical throwback: audiometric pass/fail criteria were originally based on medico-legal definitions of handicapping hearing loss, not on fitness-for-duty concerns (MacLean, 1995). However, perfectly normal hearing is not necessary to perform most hearing-critical jobs; thus, it makes sense that AFFD protocols do not require it.
The question still remains as to what level of hearing acuity is necessary to perform hearing-critical jobs. We are unlikely to arrive at a wholly satisfactory answer based on pure-tone audiometry alone. Most hearing-critical jobs require spatial awareness of sounds and speech at suprathreshold levels, often in background noise (Laroche et al, 2008). Pure-tone audiometry, on the other hand, measures monaural, peripheral auditory function in quiet. Thus, the ability to perform hearing-critical job tasks cannot be truly assessed with the audiogram alone (Marshall and Carpenter, 1988; Goldberg, 2001; Jones and Hughes, 2001). Indeed, the audiogram often under-predicts the functional performance of individuals with hearing loss (Soli, 2003).
In addition to the audiogram, some AFFD protocols include speechin- quiet or speech-in-noise tests. These so-called functional exams purportedly relate more closely to real-world function than does the audiogram. Functional testing is typically conducted if individuals do not meet pure-tone threshold criteria. For example, enlisted U.S. Army soldiers who do not meet certain audiometric criteria (e.g., due to a progressive hearing loss) are required to take the Speech Recognition in Noise Test (SPRINT; Cord et al., 1992). The SPRINT presents 200 monosyllabic words diotically under headphones at 50 dB HL in sixtalker babble at a signal-to-noise ratio of +9 dB. A percent correct score is calculated. This score, plus the soldier's length of service, are taken into account when determining whether or not changes in the soldier's assignment should be made.
Although functional exams may offer greater face validity compared with the audiogram, demonstrating the relationship between job performance and functional test results is no less difficult. Functional tests are usually conducted in a clinical or other artificial environment under conditions that bear little resemblance to actual job conditions. The ability to detect non-speech signals in noise is not evaluated, nor is the ability to integrate information usefully across the two ears for localization and environmental awareness, even though these abilities may be important on the job. To further complicate the situation, experience, skill, and familiarity with typical communications and warning signals on the job may allow an employee to compensate successfully for hearing loss (Dobie, 2001; Goldberg, 2001; Jones and Hughes, 2001). Such non-auditory influences on hearing-critical job performance cannot be evaluated with current functional tests.
One approach to avoid these pitfalls is to use tests that mimic hearing-critical situations in specific work environments (MacLean, 2001). The use of real-world simulations has high face validity and may be indicated for jobs involving life-threatening situations (e.g., combat or firefighting). Real-world simulations have the advantage of taking into account non-auditory factors, such as the availability of visual cues that influence task performance. On the other hand, the development and administration of such tests is costly and time-consuming.
In the last several years, the legality of AFFD test protocols based on pure-tone audiometry has been tested in court (e.g., Laroche, 1994; Laroche et al, 2003; Seyfarth Shaw LLP, 2006; Ceniceros, 2008). The outcomes of these cases demonstrate the tendency of the legal system to support AFFD standards that more clearly relate to job requirements. Given society's movement toward greater fairness and accountability, current pure-tone-audiometry-based protocols may eventually be supplemented or replaced with defensible protocols that offer a truer assessment of auditory fitness of duty.
References
Cord MT, Walden BE, Atack RM. (1992) Speech recognition in noise test
(SPRINT) for H-3 profile. Unpublished manuscript, Walter Reed Army Medical
Center.
Department of Defense. (2005) Medical standards for appointment, enlistment, or induction in the armed forces (DoD Instruction No. 6130.4). Washington, DC: U.S. Government Printing Office.
Dobie RA. (2001) Medical-Legal Evaluation of Hearing Loss 2nd Edition. San Diego, CA: Singular.
Goldberg RL. (2001) Hearing Guidelines for the California Commission on Peace Officer Standards & Training. Retrieved November 26, 2007 from www.post. ca.gov
Jones, CM, Hughes, KB. (2000) Hearing and vestibular disorders. In Cox, RAF, Edwards, FC, & Palmer, K ed. Fitness for Work: The Medical Aspects 3rd edition. New York: Oxford, 182-209.
LaCroix P. (1996a) Hearing standards and employment decisions: The federal model (Part one of a two-part series). Spectrum 13: 6-8.
Laroche C. (1994) Cases of possible job discrimination based on hearing loss. Canadian Acoustics 22: 89-90.
Laroche C, Giguere C, Soli SD, Vaillancourt V. (2008) Establishment of fitness standards for hearing-critical jobs. Proceedings of the 9th Congress of the International Commission on the Biological Effects of Noise, Mashantucket, CT. Laroche C, Ross MJ, Lefebvre L, Hetu R, L'Esperance A. (1993) Sound propagations of reverse alarms used on heavy vehicles. Canadian Acoustics 21:29-30.
MacLean S. (1995) Employment criteria in hearing critical jobs. Spectrum 12:20-23.
MacLean S. (2001) A practical approach to workplace communication assessment: Or "keep your head down and your ears open." NHCA Spectrum 18:12-13. Marshall L, Carpenter S. (1988, September) Hearing levels of 416 sonar technicians. (Report No. 1123). Groton, CT: Naval Submarine Medical Research Laboratory.
Seyfarth Shaw LLP. (2006) Court upholds reasonable physical requirements for safety sensitive positions. Massachusetts Employment & Labor Law Report 7:3-4. Retrieved March 23, 2008 from http://www.seyfarth.com/index.cfm/fuseaction/
Soli SD. (2003) Hearing and job performance. Paper commissioned by the Committee on Disability Determination for Individuals with Hearing Impairment, National Research Council, National Academy of Sciences.
Jennifer Tufts is assistant professor in the Department of Communication Sciences at the University of Connecticut. Previously, she completed postdoctoral clinical and research training at Walter Reed Army Medical Center in Washington DC. Her current research areas include hearing loss prevention and auditory fitness for duty in diverse populations.