Hearing Impairment

Abstract

In a 2014 study of adults aged >18 years, the US Census Bureau and the Centers for Disease Control and Prevention found that 19% of 40- to 69-year-olds reported hearing trouble and 43% of 79-year-olds reported the same.1 Almost 50% of workers in the fields of carpentry, plumbing, and mining have hearing impairment.2 Hearing impairment rating determination, described in the AMA Guides, Sixth Edition, Section 11.2a, Criteria for Rating Impairment Due to Hearing Loss (6th ed, 247–260), remains quite simple.A hearing impairment evaluation is derived from a pure-tone audiogram, and it is always based on the functioning of both ears, even though the hearing loss may be present in only 1 ear. This method is used only in adults who have acquired language skills. If the patient uses a hearing aid or other prosthetic devise, the evaluator should remove it before testing, as explained in Section 2.4e, Using Assistive Devices in Evaluation (6th ed, 25).Impairment is intended to measure permanent loss. Examiners should be aware that hearing can be temporarily impaired by recent exposure to loud noise. Under these circumstances, an audiogram should be repeated after an extended period (eg, 12–14 hours) without exposure to loud noises.Audiometers should be properly calibrated, and technicians should be appropriately trained to obtain accurate measurements. In general, audiograms are obtained measuring the decibel loss at 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz.Present audiometric techniques for measuring speech are considered limited. The frequencies 500, 1000, 2000, and 3000 Hz are considered representations of everyday auditory stimuli in the speech ranges. Therefore, these 4 frequencies (test frequencies) are used to calculate impairment ratings.The evaluator tests the individual's right and left ears at 500, 1000, 2000, and 3000 Hz. The evaluator then adds the decibel levels for each of these frequencies for each ear separately. Following this, he or she locates the total worst ear decibel level on the vertical axis in Table 11-2, Computation of Binaural Hearing Impairment (6th ed, 252–253). The total better ear decibel level is located on the horizontal axis, and the intersection of these 2 points is the total hearing impairment. To convert hearing impairment to whole person impairment, the evaluator uses Table 11-3, Relationship of Binaural Hearing Impairment to Impairment of the Whole Person (6th ed, 254). If monoauricular impairments are required, the evaluator should use Table 11-1, Monaural Hearing Loss and Impairment (6th ed, 250), and apply the total decibel levels from each ear separately.Approximately 32% of all US adults report having tinnitus at sometime.3 The prevalence of tinnitus increases through age 70 years, and about 6.4% report that the tinnitus is severe or debilitating.4 Tinnitus can be rated if there is hearing loss in the ear that impacts speech discrimination. The hearing loss need not be from the injury in question since any hearing loss, rated according to the AMA Guides, affects speech discrimination. Tinnitus is only believed to be impairing when combined with such a hearing loss. The tinnitus rating is limited to up to 5% loss. The AMA Guides states that “tinnitus in the presence of unilateral or bilateral hearing impairment may impact speech discrimination. Therefore, add up to 5% for tinnitus in the presence of measurable hearing loss if the tinnitus impacts the ability to perform activities of daily living” (6th ed, 249).The only activity of daily living that tinnitus logically affects is speech discrimination, so tinnitus should be rated only if it impacts speech discrimination.There is no correction in the hearing section for age-related loss of hearing, although it is noted that this may be apportionable. Table 1 may be used to record hearing impairment.