Invitation to Psychology

Chapter 6 Sensation and Perception 207

you are actively trying to overcome this prob-

lem. Horses, dogs, rabbits, deer, and many other

animals do not need to do this because the lucky

creatures can move their ears independently of

their heads.

A few blind people have learned to harness

the relationship between distance and sound to

navigate their environment in astonishing ways—

hiking, mountain biking, even golfing. They use

their mouths to make clicking sounds and listen

to the tiny echoes bouncing off objects, a pro-

cess called echolocation. It’s similar to what bats

do when they fly around hunting for food. In

blind human echolocators, the visual cortex re-

sponds to sounds that produce echoes—that is,

sounds that provide information about the size

and location of objects—but not to other sounds

that don’t produce echoes (Thaler, Arnott, &

Goodale, 2011).

caller’s words even when interference makes some
of the individual sounds unintelligible.
Besides needing to organize sounds, we also
need to know where they are coming from. We
can estimate the distance of a sound’s source by
using loudness as a cue; we know that a train
sounds louder when it is 20 yards away than when
it is a mile off. To locate the direction a sound is
coming from, we depend in part on the fact that
we have two ears. A sound arriving from the right
reaches the right ear a fraction of a second sooner
than it reaches the left ear, and vice versa. The
sound may also provide a bit more energy to the
right ear (depending on its frequency) because it
has to get around the head to reach the left ear. It
is hard to localize sounds that are coming from
directly in back of you or from directly above
your head because such sounds reach both ears at
the same time. When you turn or cock your head,

If prolonged, the 120-decibel music at a rock concert can damage or destroy the delicate hair cells of the inner ear
and impair the hearing of fans standing close to the speakers. The microphotograph on the right shows minuscule
bristles (cilia) projecting from a single hair cell.

Recite & Review

Recite: Hear this! Recite everything you can recall about loudness, pitch, timbre, the anatomy of

the ear, Gestalt principles as applied to hearing, and ways of determining a sound’s location.

Review: Next, go back and read this section again.

Now take this Quick Quiz:

1. Which psychological dimensions of hearing correspond to the intensity, frequency, and com-
   plexity of the sound wave?


2. Fred’s voice is nasal and Ted’s is gravelly. Which psychological dimension of hearing describes
   the difference?


3. An extremely loud or sustained noise can permanently damage the __ of the ear.


4. During a lecture, a classmate draws your attention to a buzzing fluorescent light that you had
   not previously noticed. What will happen to your perception of figure and ground?
   Answers:

Study and Review at MyPsychLab

The buzzing sound will become figure and the lecturer’s voice 4. cilia on the hair cells3. timbre2. loudness, pitch, timbre1.

will become ground, at least momentarily.