CAN YOU HEAR ME NOW?
household is filled with multiple noise
sources from kitchen appliances to
personal care products such as hair
dryers, or entertainment systems or
personal music devices.
Televisions, electronic devices, video games, and computers add to the
burden. Commuting typically involves
additional noise exposure from traffic,
sirens, buses, subway systems, and car
17 Recreational activities such
as power boating, car racing, riding
off-road vehicles, and shooting firearms
also contribute. Attending concerts,
stadium-based sporting events, playing
musical instruments,20, 21, 22 noisy classrooms, restaurants,
23 and loud toys all
play a role in modern-day noise pollution (see Table 1).
Audiologists perform a variety of
tests for auditory acuity that document
the ability to hear various levels of loud-
dB increase alone doubles the amount
of noise, and halves the recommended
amount of exposure time.
Basic hearing hygiene recommends
avoiding noises that are too loud, too
nearby, or last too long—a nearly impossible set of recommendations for
those working in a dental office.
noise meter on the NIOSH site demonstrates decibel levels versus time exposures by using common sounds. For
example, a power lawnmower operates
at 90 dB, a noise level only slightly above
that of many ultrasonic dental scalers.
To put this into perspective, NIOSH
recommends no more than two hours
of exposure to 90 dB on a daily
ADDITIONAL LIFE FACTORS
Continuous noise is a part of modern
17 Social noise exposure has tripled
over the last three decades.
2, 7 Every
The length of time one is exposed
to dangerous sound levels is also im-
portant—the longer the exposure time,
the greater the risk. In addition, the
louder the sound, the shorter the ex-
posure time before damage occurs.
According to the National Institute for
Occupational Safety and Health
(NIOSH), the maximum exposure time
at 85 dB is eight hours. In contrast, the
maximum exposure time at 110 dB, is
one minute and 29 seconds. A three
Every sound has a specific pitch or
frequency and its own loudness or
intensity. Hearing tests assess the ability to hear specific sound frequencies
from low to high pitches. Frequencies
are measured in hertz (Hz). The human
auditory system can hear a wide range
of frequencies from 125 Hz to 8,000 Hz.
Frequency levels between 2,000 Hz and
8,000 Hz are considered high frequency.
The loudness or intensity of a sound is
measured in decibels. The
decibel scale begins at zero,
which is near total silence.
Decibels are measured in a
A normal conversation
at 60 decibels is significantly
more intense than a whisper at 30 dB and sounds
twice as loud. Repeated
exposure to sounds at or
above 85 dB over time can
cause permanent hearing
loss. Noise levels at 140 dBa
can cause hearing damage
with just one exposure. An
“A-weighted” decibel, reported as a dBa, is designed
to mimic the response of
the human ear.
A variety of foam and molded earplugs.
COMMON DENTAL EQUIPMENT TESTED FOR DECIBEL LEVELS
70-74 dB Low-speed handpiece
72 dB Suction: saliva ejector against soft tissue
75 dB Suction: high-speed alone
77 dB Suction: slow-speed alone
83 dB Piezoelectric ultrasonic scaler (used), plus suction
88-102 dB High-speed handpiece
84-98 dB Auto-tuned magnetostrictive ultrasonic scaler
107 dB Piezoelectric ultrasonic scaler
Intact cochlea: The photo showing multiple chevron-shaped rows of outer hair cells and a single row of inner hair cells
in a healthy cochlea. Damaged cochlea: Extensive loss of outer hair cells and significant damage to the row of inner hair
cells. Photo courtesy of House Ear Institute.