Page 20 - Final Science BB Prep2 Part one (2nd term) 2024-2025_Neat

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Science Prep.2

G.R: The human ear can distinguish between sounds even if they are equal in intensity and
pitch.
Due to the harmonic tones that associate the fundamental tone are produced from the

source of sound

Types of sound waves

Sonic waves Infrasonic waves Ultrasonic wave

Their frequency ranged Their frequency less than 20 Their frequency more than

from 20 to 20000 Hz Hz 20000 Hz

They can be heard by They can’t be heard by They can’t be heard by human

human ear human ear ear

Ex: Sounds heard by the Ex: Sounds produced Sounds produced

human ear before rainfall by bats & dolphins and dogs

Note:

Some animals such as bats, dogs and dolphin can hear the ultrasonic waves.
Give reason:

1- The human ear can hear sounds of frequency ranging from 20 to 20000 Hz.

Bec. The ear transmits the effect of these waves to the brain which translate them
into sound and audible tones.

2- Dogs can hear all sounds produced by man.

Bec. Dogs can hear sounds of frequency up to 50000Hz (50 kilohertz).

3- Man can’t hear sounds produced by dolphins

Bec. Dolphins produce sounds up to 120000 Hz (120 kilohertz) while man can hear

sounds up to 20000Hz (20 kilohertz)

4- Sonic wave can be heard by human ear (audible)?

Because their frequency ranges from 20 to 20000 HZ which affects the human ear.

5- Ultrasonic waves are non-audible sound waves?

Because their frequency range is more than 20000 HZ which doesn’t affects the

human ear.

6- Infrasonic waves are non-audible sound waves?

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Because their frequency is less than 20 HZ which doesn’t affect the human ear.