Other Ear Problems Support Group

The principal damage mechanism to the human ear in industrialized society is exposure to elevated sound levels. Approximately ten percent of the population in industrialized societies have significant hearing loss or tinnitus, and millions more are steadily progressing to that outcome. Once it was thought that only extremely high sound levels create hearing loss; however, more careful investigations showed that cumulative exposure to relatively moderate levels, such as 70 dB(A), can lead to the irreversible loss of hearing or tinnitus. Another myth of noise effects is the overstated role of presbycusis, or loss of hearing associated with aging. It has been demonstrated that the most important factor of hearing degradation is not aging alone, but rather the cumulative long-term exposure to environmental and occupational noise that create the harm. In the Rosenhall study, age cohort populations were tracked, with the result that noise-exposed persons had greater hearing loss than their age cohorts who were relatively unexposed to noise. In fact, it has been shown that people in non-industrialized countries do not experience the same progressive hearing loss.

The mechanism of hearing loss or tinnitus arises from trauma to stereocilia of the cochlea, the principal fluid-filled structure of the inner ear. The pinna (visible portion of the ear) combined with the middle ear amplifies sound pressure levels by a factor of twenty, so that extremely high sound pressure levels arrive in the cochlea, even from moderate atmospheric sound stimuli. The cilial damage is known to be cumulative and can be irreversible. The most recent research indicates that high noise levels create elevated levels of reactive oxygen species in the inner ear, which interfere with the regenerative process for cochlear cilia repair. This research shows why high noise levels have differing effects over a given population, and lead to a possible preventative strategy of adequate anti-oxidant intake.

In 1972 the U.S. EPA told Congress that at least 34 million people were exposed to sound levels on a daily basis that are likely to lead to significant hearing loss. The worldwide implication for industrialized countries would place this exposed population in the hundreds of millions.