unit ( 2) grade ( 6 )

unit 2 :

Sound Lesson 1 :

Sound Waves And HearingBy

Mr / Ismail Etman

A vibration : • is a complete back and forth motion of an object, as in the

longitudinal waves.

What is sound?

• Your brain interprets the vibrations in the air as sounds.

05/02/2023MR / ISMAIL ETMAN 2

Sound wave : is a longitudinal wave that caused by vibration travels through a medium.

Sound wave travels by vibrating the particles of the medium.

The particles of the medium do not move with the sound wave, It just vibrates back and forth along the path that the sound wave travel.

Sound wave moves through solid faster than water, faster than air.

Sound wave does not moves through the vacuum.Because, There is no particles in the vacuum.



How do the humans hear sound?


Pitch: is how high or low you think a sound is.

- It depends on the frequency and the wavelength of the sound.

Higher frequency

shorter wavelengt

h

higher pitch


Loudness : is measure of how well a sound can be heard.

- It depends on the amplitude of the sound wave.

- &

- The unit of measuring is decibel (dB). 1 bel = 10 decibels.

greater amplitude

louder sound

smaller amplitude

softer sound


The amplitude:

• The maximum distance that the particles of a wave's medium vibrate from their rest position.


Doppler Effect :• Is the change of the observer frequency when the sound source, the

observer, or both are moving.


Questins: • Two fire trucks with sirens on speed towards and away from an observer

as shown below.

a) Which truck produces a higher than normal siren frequency? __________b) Which truck produces a lower than normal siren frequency? ___________

05/02/2023 10

Questins: 1.Circle the letter of each statement about the Doppler Effect that

is true.a. It occurs when a wave source moves towards an observer.b. It occurs when an observer moves towards a wave source.c. It occurs when a wave source moves away from an observer.d. It occurs when an observer moves away from a wave source.

2.The ______________ of sound is directly related to its intensity. a. Pitch b. Loudness c. Amplitude

MR / ISMAIL ETMAN

unit 2 :

Sound Lesson (2)

Interactions of Sound Waves


What affects the speed of sound?

1) The Type of Medium: Sound travels fastest through solids,

Slower through liquids,

Slowest through gases.

2) The Temperature of The Medium:Higher temperature of a medium,

greater speed of a sound through it.


INTERACTIONS OF SOUND WAVES WITH THE MATTER:1.Reflection of Sound Waves:

•The bouncing back of a wave when the wave hits the barrier.

- Smooth and hard surface is the best reflected surface.

•


2. Absorbance of Sound Waves:- A rough wall will absorb sound better than a smooth wall will.

- A soft materials absorb sound better than hard materials do.


3. An Echo: is a reflected sound wave.- Rough materials reduce echoes by scattering sound waves.

Echolocation:

the use of reflected sound waves to find objects.

- Examples : of using echolocation. Sound navigation and ranging ( sonar ). Some animals ( bats ,….).


INTERFERENCE:• happens when two or more waves overlap and

combine to form one wave. two sound

waves

nearly equal frequencies

Constructive

Interference

Destructive

Interference

not quite equal

frequencies

beats

05/02/2023 17

INTERFERENCE:Constructive Interference:

When waves overlap and combine to form a wave with a larger amplitude.

Produce a louder sound.

Destructive Interference: When waves overlap and combine to form

a wave with a smaller amplitude.- Produce a softer sound.

Examples: headphone.

MR / ISMAIL ETMAN


INTERFERENCE:

oBeats : When the two sound waves have not quite equal frequencies .

05/02/2023 19

Resonance:- When a sound wave matches the natural frequency of an object to vibrate.

MR / ISMAIL ETMAN

unit ( 2) grade ( 6 )

Education