Understanding Psychology (10th Ed)

Balance: The Ups and Downs of Life
Several structures of the ear are related more 
to our sense of balance than to our hearing. Collectively, these structures are known 
as the vestibular system, which responds to the pull of gravity and allows us to main-
tain our balance, even when standing in a bus in stop-and-go traffi c. 
The main structure of the vestibular system is formed by the
 semicircular canals 
of the inner ear (refer to Figure 1 on page 115), which consist of three tubes contain-
ing fl uid that sloshes through them when the head moves, signaling rotational or 
angular movement to the brain. The pull on our bodies caused by the acceleration 
of forward, backward, or up-and-down motion, as well as the constant pull of grav-
ity, is sensed by the otoliths , tiny, motion-sensitive crystals in the semicircular canals. 
When we move, these crystals shift as sands do on a windy beach, contacting the 
semicircular canals
Three tubelike 
structures of the inner ear containing 
fl uid that sloshes through them when 
the head moves, signaling rotational or 
angular movement to the brain.
Study Alert
Be sure to understand the dif-
ferences between the place 
and frequency theories of 
hearing.
High pitch
Frequency (in kilohertz)
Highest note
on a piano
Low pitch
New
text-message
ringtone
Range by age group
Audible frequencies for
sound at 60 decibels
SPL (sound pressure level)
50–59 years old
40–49
30–39
18–24
20
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
19
FIGURE 3 
Some teenagers set their text-message ring tone to a frequency too high for most 
adults to hear, allowing them to use cell phones where they are prohibited. 
(Source: Vitello, 2006.)
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