Download Sensation and Perception Chapter 4

Hearing
 The vibrational energy of vibrating objects, such as
guitar strings, transfer the surrounding mediumair-as the vibrating objects push the molecules of
the medium back and forth.
 In space, there is no air, so the sound wave would have no
medium to push. Any explosion would be eerily without
sound.
Hearing
Frequency and Amplitude
 There are two physical characteristics of sound:
frequency and amplitude.
 Frequency: The number of cycles completed by a wave in a
given amount of time.
 Amplitude: The physical strength of a wave.
 Pitch: This is
how high or
low a sound
seems.


A bird makes a
high pitch.
A lion makes a
low pitch
 Sounds also
are different
in how loud and
how soft they
are.
Sound.
Quality.
 Pitch and loudness
are two ways that
sounds are
different.
 Another way is in
quality.
 Some sounds are
pleasant and some
are a noise.
Getting Started
 Draw two pictures of sound waves showing the
following


Two waves with a different pitch but the same loudness
Two waves with different loudness but the same pitch
If a tree falls in the forest…
 The question “If a tree falls in the forest and there
is no one around to hear it, does it still make a
sound?” can now be answered.
 No, it would make no noise.
 Sound is a purely psychological sensation that
requires an ear (and the rest of the auditory
system) to produce it.
Parts of the ear
 Eardrum: Structure at the end of the ear canal that
vibrates to transmit messages to the inner ear
Parts of the ear
 Cochlea: Inner ear that contains fluids and neurons
that change vibrations to the sounds we hear
Parts of the ear
 Auditory Nerve: carries the cochlea's message to the
brain
Deafness
 There are generally two types of deafness.
 Conduction deafness is an inability to hear,
resulting from damage to the structures of the
middle or inner ear.
 Nerve deafness (Sensorineural Deafness) is
an inability to hear, linked to a deficit in the body’s
ability to transmit impulses from the cochlea to the
brain.
How the Other Senses are Like
Vision and Hearing
 Each gives us information about a different aspect
of our internal or external environment. Yet each
operates on similar principles.
 Each transduces physical stimuli into neural
activity and each is more sensitive to change than
to constant stimulation.
Our Senses
 You will notice that all of our sense organs are very
much alike. They all transform physical
stimulation (such as light waves or sound waves)
into the neural impulses what give us sensations
(such as light and dark).