d. Properly fitted earplugs will not cause damage to the normal ear canal if the
earplugs are kept reasonably clean. Plugs should be fitted individually for each ear,
under medical supervision (see Figure 3-9). Occasionally, an individual's two ear canals
will require earplugs of different sizes. A good seal between the ear canal and the
earplug is very important, so that no leak develops. A really good seal may cause some
initial discomfort to the wearer. When earmuffs are chosen in preference to earplugs,
the headband must be properly adjusted to ensure a snug fit. When eyeglasses are
worn at the same time as earmuffs, it is important that the flange of the muff fit well
around the temple of the glasses, because even a small "leak" will completely destroy
the purpose of the ear protector, yet the wearer will have a false sense of security
because of wearing the protector. A related problem with earplugs is that they tend to
work loose as a result of talking and chewing. As a result, they must be reseated from
time to time during the workday.
Figure 3-7. Type I earmuffs.