Warm-UP: Complete KWL chart on Sound What do you know? What do you want to know? What do you want to learn?

What type waves are produced by the n
oise

from a tuning fork?


Warm
-
UP:

Complete KWL chart on Sound


What do you
know
?


What do you
want

to know?


What do you want to
learn?

•
are waves produced by
vibrating objects that
travels through a gas,
liquid, or solid.

•
Are
compression waves

•
Travel as
vibrations

moving through
the air as a compression wave

•
Travel
through air
, but travel through
other materials.

•
Slinky
–

example of compression
waves.


•
What is an example of an animal that
sends out sound waves under water?


•
Whales

communicate through long
distances by producing sounds under
water


2.1 Facts about Sound C
-
37
-

(P13IN)


Sound :

•

is a mechanical wave

•

is a vibration that travels through
gas, liquid, or solid p. C 40
-
41

•

is a longitudinal wave

•

transfers energy through a medium

•
speed depends on its medium p.C
-
42


How Sound Waves are Produced? C38

•
Sound waves are produced by vibration
that are usually too small to see.

•
Vibrations push and pull on the
medium around them

•
Vibrations send waves out in all
directions

•
Vocal cords are sound making
instruments in the body
.

When are your vocal cords tensed up
and when are they relaxed? P. C 39

•
Vocal cords are tense when you are
about to speak or sing.

•
Vocal cords are relaxed when you are
breathing to allow air to pass in and
out of your windpipe.

•
End of notes for 2.1

2.2 Frequency Determines Pitch

Description of Pitch ( write on page 15)

•
the quality of highness or lowness

•
Is determined by frequency

•
A low
-
frequency makes a low pitch

•
A high frequency makes a high
-
pitch

•
Rapidly vibrating object makes a high
sound

•
Slowly vibrating object makes a low
sound




Which diagram represents:

1. High Pitch? 2. Low Pitch

Washer (larger, small), ball, cork


A.


B.

Activity
-

Hit several objects against a tuning
fork and try to identify the objects by sound
[large and small washer, ping pong ball,& cork]

High and Low Frequencies


•
Most humans with good hearing can
hear in a range of 20 hertz to 20,000
hertz

•
Elephants may use infrasound
–

sound that travels through the
ground , hearing another elephant
20 miles away.

•
Ultrasound is above 20,000 hertz and
can be used for communication, find
food, image internal body parts and
detect objects


Natural Frequencies

•
A tuning fork has a natural
frequency and can be used
to tune a piano

•
Each musical instrument
and each human voice has it
own particular sound called
sound quality or timbre


The Doppler Effect

•
Motion causes the sound you hear
from a passing vehicle such as a train
to seemingly change its pitch
(highness or lowness of sound).

•
Frequency and Pitch

•

The sound from a fire truck that is
far away
reaches you ear at a low
frequency. When the vehicle is
S
, the
frequency is greater and the pitch is
higher.

End Notes for 2.2

15.2 The Doppler effect

•
The shift in frequency caused by
motion is called the
Doppler effect
.

•
It occurs when a sound source is
moving at speeds less than the speed
of sound.

What is Resonance?

Many objects have a
natural
frequency

–

vibrates in a regular
pattern. (swings and pendulums)

What is Resonance?

Many objects have a
natural frequency

–

vibrates in a regular pattern. (see saw
and pendulum)

Resonance

occurs whenever a sound
wave has the same frequency as the
natural frequency of an object. The
sound will cause the object with the
same
natural frequency

to vibrate.

What is Resonance?

Many objects have a
natural frequency

–

vibrates in a regular pattern. (see saw
and pendulum)

Resonance

occurs whenever a sound
wave has the same frequency as the
natural frequency of an object. The
sound will cause the object with the
same
natural frequency

to vibrate.

End Notes for 2.2

Sonic Boom


Read the caption on page C 44


The Look of Sound

Digital Sampling of frequency from
sound waves

2.3 Intensity Determines Loudness

•
Intensity Depends on the amplitude of a sound
wave

•
. As the amplitude of a sound decreases, the
frequency stays the same.

•
When you take away energy or add energy to a
sound wave, you change its intensity without
changing its quality

2.3 Facts about Amplification

•
Amplification

•
Increases the strength of an electrical signal

•
Is often used to increase the intensity of a
sound wave

•
Is experienced when you listen to a TV, radio
or stereo

As an
amplifier increases
the sound,
the amplitude of the wave increases.

One String Guitar


One String Guitar

Activity


Construct a single stranded guitar to determine which pitch is higher.

Number each distance 1
-
3 using 1 =lowest , 2= medium 3 = highest?


________10 cm, _______ 15 cm or ______20 cm


Observe the vibration of the rubber band. At what distances are vibrations faster?



________10 cm, _______ 15 cm or ______20 cm




2.3 Main Idea about Acoustics

•
Acoustics is the scientific study of sound

•
Acoustics


Involves how sound is produced


Involves how sound is received and heard


Refers to the way sound waves behave
inside a place


2.3 Intense Sound Can Damage
Hearing

•
Intense sounds can damage and destroy


hair cells inside the inner ear called the


cochlear.

•
Hairs cells make hearing possible

•
Ear damage can be lessened by wearing ear


plugs or covering the ear

Operation of the Cochlea


When vibrations form, sound waves enter the outer ear and then passes to the eardrum.


The eardrum vibrates against the middle ear bones (hammer, anvil and stirrup) and is then


transferred to the cochlear. Within the inner ear, there are tiny hairs that vibrate back and for


with in the cochlear transmitting tiny electric signals to the braid.

Common Sounds and their Loudness

Using Sound

What is
Acoustics
?

Acoustics

is the study of sound and ways to optimize the
hearing of sound inside various structures.


Spring 2006

UCSD: Physics 8; 2006

29

Example Sound Speeds

Medium

sound speed (m/s)

air (20

C)

343

water

1497

gold

3240

brick

3650

wood

3800
–
4600

glass

5100

steel

5790

aluminum

6420

http://hypertextbook.com/physics/waves/sound/

Resources
-

http://www.proteacher.org/c/657_Light_and_
Sound.html


Sound Waves

A
sound wave

is the result of vibrations producing
alternating
high
-
pressure and low
-
pressure regions of air.

A vibrating turning fork
produces longitudinal waves.

OSHA Regulation
–

Exposure




140







120







100






























80



Decibel






60








-

Noise Control Program






















40













































-

Hearing Conservation






20
















0 2 4
6 8




Exposure Duration (Hours)


End 2.3
notes

2.4
What is Echolocation?


When organisms send out
ultrasound waves and then
interpret the returning echo, it is
called echolocation.



Uses of echolocation
?

Dolphins and bats use echolocation to:


•
hunt for food

•
Locate objects

•
Locate offspring and other like organisms


•
Bats send out a chirp

•
Dolphins, toothed whales and porpoises send out
ultrasound clicks or squeaks

What is sonar
? Man uses the principle of echolocation
called sonar.

Sonar

is a system that uses the reflection of underwater
sound waves to detect objects. This has been used to find
sunken ships and schools of fish.

15.1 Recording sound

5.
The electrical signal is amplified until it is powerful enough to
move the coil in a speaker and reproduce the sound.

Sound waves are l
ongitudinal
Waves
have compression
(high)
and rarefaction (low) areas of air pressure

Waves such as light, x
-
rays, and other forms of radiation
do not require a medium.

Review

What are mechanical waves?

Mechanical waves are waves which require a medium.
A medium is a form of matter through which the wave
travels (such as water, air, glass, etc.)


Sound is a mechanical wave