Download Chapter 10: Sound - Newark Catholic High School

Chapter 10: Sound
For this chapter we will have a vocabulary quiz and a
chapter test.
Vocabulary:
Eardrum
loudness
music
resonator
echolocation
sonar
doppler effect
Cochlea
decibel
sound quality
acoustics
intensity
pitch
overtone
ultrasound
Section 1: The Nature of Sound
sound waves occur when a vibrating object produces a wave
when a radio speaker vibrates, it collides with some of the
particles in the air, transferring energy to those particles.
they collide with other particles, transferring energy to form a
sound wave.
Sound waves are longitudinal
they can travel through liquids and solids as well as air,
though they move slower.
the speed of a sound wave through a medium depends on
that medium's composition and state (whether it is a solid,
liquid, or gas).
The temperature, density, and elasticity of the medium also
affect the speed of sound.
On page 307 there is a table that gives the speed of sound
in different mediums.
As the temperature of the medium increases, the speed of
sound increases
As the density of the medium increases, the speed of sound
increases
As the elasticity of a medium increases, the speed of sound
increases
THE EAR
Your ears and brain work together to interpret sound waves.
the ear has three sections: The outer ear, middle ear, and
inner ear.
The outer ear- made up of the visible part of your ear, ear
canal, and ear drum
- gathers sound waves
- moves sound waves into the ear canal (about 2-3
cm long)
- leads to eardrum
Eardrum is a tough membrane about 0.1 mm thick that
transmits sound from the outer ear to the middle ear
The middle ear- sound waves transferred from vibration of
eardrum to bones in middle ear
- 3 bones that vibrate, the hammer, the anvil, and
the stirrup.
- bones make a lever system that increases force
and pressure from the sound wave, amplifying the sound
wave
-stirrup is connected to a membrane called the
oval window, which vibrates as the stirrup vibrates
The inner ear- when the membrane in the oval window
vibrates, the sound vibrations are transmitted into the inner
ear.
- contains the cochlea- a spiral shaped structure
that is filled with liquid and contains tiny hair cells.
- when the hair cells in the cochlea vibrate they
send nerve impulses to the auditory nerve in the brain.
Hearing losswhen a person's hearing is damaged it is usually
because the tiny hairs in the cochlea are damaged or
destroyed-usually by loud sounds
the damage from hearing loss is permanent, the hair cells in
the cochlea do not grow back when damaged or destroyed.
HW: p 310 # 1-5
.
Section 2: Properties of Sound
The degree of disturbance from a wave connects to its
amplitude.
for a longitudinal wave the amplitude is how close together
particles are at the compressions and how far apart they are
at the rarefactions.
to make a sound wave with a greater amplitude, more
energy must be put into the wave.
When you adjust the volume of sound, you are adjusting the
amplitude of the waves. We call it the intensity.
intensity is the amount of energy that passes through a
certain area in a specific amount of time
When you turn down the volume on your stereo, you reduce
the energy carried by the wave, so you reduce the intensity
of the wave.
Loudness is the human perception of sound volume, and
primarily depends on sound intensity.
people may not agree on loudness, because their
perceptions are different.
Because of this, it is hard to say how loud is too loud.
There is a measurement scale to describe the intensity of
sound, that gives us an idea of the loudness.
A Decibel (dB) is a unit of sound intensity.
Sustained sounds above 90 dB can cause permanent
hearing loss, and short sudden sounds above 120 dB can
cause pain and permanent hearing loss.
Common sounds in decibels:
Rustling leaves
Purring Cat
Air Conditioner
Cafeteria
Rock Concert
Pain Threshold
Jet Plane take off
20 dB
25 dB
50 dB
80 dB
110 dB
120 dB
150 dB
Pitch is how high or low a sound seems to be.
Pitch is what we read when we sing, or play an instrument.
the pitch of a sound is related to the frequency of the sound
wave.
The higher the frequency (the more waves pass by in a
second) the higher the pitch!
The Doppler Effect
The Doppler effect is the change in wave frequency due to a
wave source moving relative to an observer.
.