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Hearing
Our sense of hearingworks in stages.
The three sections of your ear— the
external,middle and inner ear— act as
an intake system.
The outer part of the ear, called the
pinna, is thefleshy, visible part. The
pinna collects soundwaves and trans-
mits them to themiddle ear through the
auditory canal.At the end of the
auditory canal in themiddle ear is a thin
layer of skin called the eardrum. Like
a drum, it vibrateswhen hitwith sound
waves. The vibration of the eardrum
causes three small bones tovibrate
themalleus (hammer), incus (anvil)
and stapes (stirrup).
Sound then travels to the cochlea in
your inner ear. The cochlea looks like
a small snail and is full of fluid, which
shifts as youmove.When sound travels
to the cochlea, it causes thefluid to
vibrate. The auditory nerve carries
these vibrations to the brain in
electrical pulses. This is also the part
of the ear responsible for helping us
maintain balance.
Pitchperfect
Pitch is the frequency of a soundwave
measured in cycles per second, or
hertz (Hz). Someonewith perfect
pitch can identify tones, keys
ormusical noteswithout any
reference note.Although fewer
than 1 in 10,000 people have perfect
pitch, speakers of tonal languages such
asVietnamese andMandarinChinese
show higher accuracy in pitch, because
it is important in conveyingmeaning
in these languages.
The human hearing range is
20–20,000Hz.Many animals,
including cats and dogs, that are
dependent on sounds for hunting
can hear frequencies of up
to 20,000Hz. Dolphins
and bats can hear
frequencies of up to
100,000Hz!
What’s that
sound?
Have you or someone you know
ever heard ringing in your ears?
This is tinnitus, and it affects 1 in 5
people. The ringing (or buzzing, hissing
or chirping) can range from quiet
to loud, and can occur intermittently
or continuously.
Exposure to loud sounds for an
extended period of time is themost
common cause of tinnitus. Pilots,
constructionworkers,musicians and
anyonewhoworkswith loudmachines
or instruments is at risk. Even a single
exposure, such as a loud concert,
can cause tinnitus. In fact, 1 in 5
adolescents has hearing loss.
Lower thevolume
It’s important to protect your
hearing. Earbuds, or earphones that
fit into your ears, are one of themain
causes of hearing loss in adolescents.
If you use headphones to listen to
music, use a type that do not fit inside
the ear.Andkeep the volume low; if you
arewearing earbuds and the person next
to you can hear themusic, you’re
playing it too loud.
Here
are some
common
sounds
measured
in decibels.
Faint
Whisper
20
Quiet library
30
Moderate
Quiet room
40
Rainfall
50
Typical conversation 60
Dishwasher
60
Very loud
Busy traffic
70
Vacuum cleaner
70
Hair dryer
90
Blender
90
Subway train
90
Extremely loud
Hand drill
100
Gas lawnmower
106
Rock concert
110
Painful and
dangerous
Jet taking off
120
Jackhammer
130
Jet engine
140
Fireworks
(at 3 feet away)
150
Soundbites& taste testing
Talking tubes
What youneed: Plastic tubing 6 to 8 feet in length (available at
hardwareor pet stores); two funnels;masking tape
1. Stand 6 to8 feet away from a friend and take turnswhispering
to eachother. Can youhear eachother?
2. Attach a funnel to each endof the plastic tubeusingmasking
tape. Raise the tube andput your ear up to the funnel; have a
friendwhisper to you from the other funnel, and thenwhisper to
your friend. Now can youhear eachother?
As you learned, the ear is similar. Sound enters through the funnel
(pinna) and travels through the tube (auditory canal).When your
friendwhisperedwithout the aidof the funnel, youprobably heard
thewhispering, but not the specificwords. Thewhispering created
vibrations; otherwise, youwouldnot haveheard anything.When
youused the tube, the soundwaves traveled through the air and
the funnel, demonstrating that sound travels.
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