To standardize the way in which severity of hearing loss is reported, WHO has
adopted a grading system based on audiometric measurements. This system is
a revision of an earlier approach adopted by WHO, and differs from the earlier
system in that measurement of onset of mild hearing loss is lowered from 26 dB
to 20 dB; hearing loss is categorized as mild, moderate, moderately-severe, severe,
profound or complete; and unilateral hearing loss has been added. In addition
to the classifications, the revised system provides a description of the functional
8 Audiograms show the minimum intensity, in decibels, a person can hear at different frequencies of sound. This is typically depicted
in graph form following a hearing test, as measured by an audiometer.
38 WORLD REPORT ON HEARING
consequences for communication that are likely to accompany each level of severity (148).
This revised grading system is presented in Table 1.3 below.
The classifications used in Table 1.3 follow the recommendations of the International
Classification of Functioning, Disability and Health (ICF) proposed by WHO in 2001.
As stated in the ICF, a person with the slightest reduction in hearing sensitivity has
a potentially “disabling” condition. The ICF defines a person’s state of health along
three dimensions which are outlined in Box 1.1 (158). According to the ICF, the
disability experienced is determined not only by the individual’s hearing loss but also
by the physical, social and attitudinal environment in which the person lives, and
the possibility of accessing quality EHC services. Therefore, a person with hearing
loss who does not have access to hearing care, is likely to experience far greater
limitations in day-to-day functioning and thus higher degrees of disability.