Environmental Engineering Reference
In-Depth Information
At one time, exposures to sounds above 85 dBA were limited to occupational
settings, but in modern society, sounds that we hear in our everyday environment,
e.g., passing traffic, roaring construction drills, loud subway stations, and sirens,
among others, are exposing our ears to levels exceeding 85 dBA. Such continuous
exposure over many years does affect the aging ear. The League for the Hard of
Hearing in New York City collected hearing data over a period of 19 years. The
League took measurements of over 27,000 older citizens, ranging in age from 60
to 89 years and found that the percentage of individuals who failed the hearing
screening test increased with each passing year. It was hypothesized that the city's
increased noise over the years accounted for the accelerated hearing loss in the older
citizens [12].
Actually the threat to hearing begins early in life. Over 20 years ago, health
professionals began to recognize the hazards of loud sounds in neonatal intensive
units. Infants who were exposed to the loud sounds of these units suffered some
hearing loss and delayed growth and development [13]. Studies suggest that chil-
dren are more vulnerable to loud sounds than adults. That is one reason Nancy
Nadler of the League for the Hard of Hearing warned parents to listen to toys before
purchasing them. She noted that rattles and squeaky toys for very young children
and the drums, horns and electric guitars preferred by older children can emit very
loud sounds [14]. Brookhouser reported that as many as 80% of elementary school
children use personal music players, many for extended periods of time and at poten-
tially dangerously high volumes [15]. This is a practice that parents should strictly
discourage. In 2001, it was estimated that 12.5% of American children aged 6-19
years had impaired hearing in one or both ears [16]. In a more recent study, Agrawal,
et al. found that hearing loss was growing in the United States, with the rise not just
amongst older people, as might be expected, but amongst people between the ages of
20 and 29 years. The authors also found that the risk for hearing loss was greater in
people who smoked; were exposed to occupational, leisure-time, or firearm noise; or
had hypertension or diabetes [17]. Plakke, in his study of two video arcades, found
that certain games reached levels of 111 dBA [18]. Like youngsters in the eighties,
young people today still enjoy visiting video arcades and, undoubtedly, are subject-
ing their ears to high levels of sound. Thus, it shouldn't be surprising that Holgers
and Petterson reported that leisure time noise exposure correlated with tinnitus in
students aged 13-16 years [19]. Also, young adults responding to a web-based sur-
vey reported experiencing tinnitus or impaired hearing after exposure to loud music
at concerts or in clubs [20]. The Royal National Institute for the Deaf found that the
hearing of nearly 70% of the people who visited nightclubs were adversely affected,
with loud music damaging the hearing of nearly 50% of pub goers and up to 90% of
young people experiencing symptoms that suggest hearing damage, such as tinnitus
or decreased auditory acuity after a night out [21].
People working in clubs, bars and other places of entertainment are also at risk
for hearing loss [22]. Nearly a third of students who worked part time (bar staff
or security staff) in a university entertainment venue were found to have perma-
nent hearing loss of more than 30 dB [23]. Pete Townsend of the WHO band had
often talked of his hearing loss and hearing impairment is often seen in amateur
