Properties of Sound Waves

UNIT 4 WAVES

Lesson 11: Properties of Sound Waves (part 1)

6.P.1 Understand the properties of waves and the

wavelike property of energy in earthquakes, light and

sound waves.

6.P.1.3 Explain the relationship among the rate of vibration, the
medium through which vibrations travel, sound and hearing.

What are some
ways that you
could describe

sounds?

Sound Waves

Properties of Sound Waves
Intensity
Loudness
Frequency
Pitch

PHET Simulation: Wave on a String

Observe what

happens when you
move the wrench

up and down

slowly versus when
you move it up and
down quickly with

a lot of energy.

​ https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html

Audio Response

What did you observe (slow movement)?

Open Audio Recorder

Audio Response

What did you observe (quick movement)?

Open Audio Recorder

Sound Waves

Properties of Sound Waves
• Intensity – the amount of

energy the wave carries per
second through a unit of area

• Amplitude increases with

increased energy

• Measured in watts per

square meter (W/m2)

Sound Waves

Properties of Sound Waves
• Loudness – how strongly

audible something sounds to
you; how you perceive it

• It is often confused with

volume. Volume is how you
manipulate or change how
loud something is.

• The higher the amplitude, the

louder something will sound.

Sound Waves

Properties of Sound Waves
• Loudness or sound intensity

is measured in decibels
(dB).

• Decibels shows the amount

of air pressure displaced by
sound, which affects how it
hits your eardrum and its
perceived level of loudness.

• Maximum safe level is 85

dB

UNIT 4 WAVES

Lesson 12: Properties of Sound Waves (part 2)

6.P.1 Understand the properties of waves and the

wavelike property of energy in earthquakes, light and

sound waves.

6.P.1.3 Explain the relationship among the rate of vibration, the
medium through which vibrations travel, sound and hearing.

SOUND WAVES AND
THEIR PROPERTIES

Open Ended

What is high intensity and how does it affect sound loudness?

I CAN…

▹Identify the
characteristics of sound
waves.

▹Explain how sound
travels.

▹Describe the Doppler
effect.

13

What was the

loudest sound that

you heard
yesterday?

3

Open Ended

What is low intensity and how does it affect sound loudness?

Multiple Choice

A sound wave is what type of wave?

• Compressional

• Transverse

• Electromagnetic

Open Ended

What was the loudest sound that you heard yesterday?

7

When an object vibrates, it exerts a force on the
surrounding air. For example, as the end of the
tuning fork moves outward into the air, it pushes
the molecules in the air together.

Music Lab Experiment

Observe what

happens as you
touch each of
the piano keys.

Make

observations for

what you see

and hear.

​https://musiclab.chromeexperiments.com/Sound-Waves/

8

As a result, a region where the molecules
are closer together, or more dense, is
created. This region of higher density is
called a compression. When the end of the
tuning fork moves back, it creates a region
of lower density called a rarefaction.

Open Ended

What did you hear?

Making Sound Waves

Like other waves, a sound wave can be described by its wavelength and frequency. The wavelength of a sound wave is shown below. The frequency of a sound wave is the number of compressions or rarefactions that pass by a given point in one second. An object that vibrates faster forms a sound wave with a higher frequency.

9

Open Ended

What did you see?

Poll

Letter C is what part of the wave?

• Rarefaction

• Compression

• Wavelength

Pitch and Frequency

Multiple Choice

Letter B is what part of the wave?

• Rarefaction

• Compression

• Wavelength

Sound Waves

Properties of Sound Waves
• Frequency – the number of

vibrations that occur per
second

• Wavelength changes with

frequency

• Measured in Hertz (Hz)
• 50Hz = 50 vibrations per

second

17

Sound Waves

Properties of Sound Waves
• Frequency – the number of

vibrations that occur per
second

• Wavelength changes with

frequency

• Measured in Hertz (Hz)
• 50Hz = 50 vibrations per

second

Multiple Choice

Sound waves travel fastest in ______.

• Air

• Water

• Steel

• Glass

Multiple Choice

Which wave has the greatest frequency?

• blue

• Red

• orange

• Green

18

Sound Waves

Properties of Sound Waves
• Pitch – a description of how high

or low the sound seems to a
person

• High frequency = high pitch
• Low frequency = low pitch
• Example: a young girl might

have a squeaky (high pitched)
voice, an older man might have
a deep (low pitched) voice

20

What determines the loudness of different sounds?

The amount of energy a wave carries depends on its amplitude. For a compressional wave such as a sound wave, the amplitude is related to how spread out the molecules or particles are in the compressions and rarefactions (seen as expansions below).

21

Multiple Choice

Which wave is the loudest?

• blue

• Red

• orange

• Green

22

Multiple Choice

Which wave is the quietest?

• blue

• Red

• orange

• Green

24

Multiple Choice

Which wave has the highest pitch?

• blue

• Red

• orange

• Green

Multiple Choice

The ______ of a sound is how high or low it sounds.

• Pitch

• Frequency

• Amplitude

• Loudness

Multiple Choice

Which wave has the lowest pitch?

• blue

• Red

• orange

• Green

Multiple Choice

A tone that is lower in pitch is lower in what characteristic?

• Amplitude

• Frequency

• Wavelength

32

Multiple Select

• A

• B

• C

• E

• F

Multiple Choice

The change in frequency that occurs when a source of sound is moving relative to a listener is known as what?

• Doppler Effect

• Loudness Effect

• Pitch Effect

• Amplitude Effect

Sound WavesWhich waves have the highest pitch?

Drag and Drop

Which waves are the loudest?​ ​ ​ ​ ​

Placeholder

Placeholder

Drag these tiles and drop them in the correct blank above

C

E

B

D

A

F

Multiple Choice

What is a reflected sound wave?

• Echo

• Refracted

• Pitch

• Loudness

Drag and Drop

Which waves are the quietest?​

Placeholder

​

Placeholder

Drag these tiles and drop them in the correct blank above

B

D

A

C

E

F

Multiple Choice

The energy carried by sound waves increases as amplitude increases.

• True

• False

Drag and Drop

Which waves have the highest pitch?​

Placeholder

​

Placeholder

Drag these tiles and drop them in the correct blank above

B

F

A

C

E

D

Drag and Drop

Which waves have the lowest pitch?​​

Placeholder

​

Placeholder

​

Placeholder

Drag these tiles and drop them in the correct blank above

C

D

A

E

F

B