SOUND

MADE BY HASHIM ALI

Definition of Sounds

i. vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear.

ii. Any object that vibrates produces sound….!

iii. A vibration is a movement about a fixed point.

WAVES

i. A wave can be described as a disturbance that travels through a medium from one location to another location.

TYPES OF WAVES

I. Transverse Waves 2. Longitudinal Waves Particles vibrate perpendicular to the Particles vibrate parallel to the direction of wave. direction of

wave. Examples: Light and water Examples: Sound and spring

SPEED OF SOUND

i. The sounds travel the fastest in solids because the particles are close together…..

ii. Speed of sound in solids is 5,000 m/s.

iii. Whereas in liquids, it is 1,500 m/s and 330 m/s in gases.

Why can’t sounds travel through a vacuum?

i. Sound cannot travel through a vacuum.

ii. A vacuum is an area without any air, like space.

iii. So sound cannot travel through space because there is no matter for the vibrations to work in.

Detecting Sound Waves

I. The ear is the organ of hearing

II. It is usually described as having three parts :

III. the outer ear, the middle ear and the inner ear.

IV. The word ‘ear’ itself refers to the external part.

V. The eardrum is the membrane of the middle ear, which vibrates in response to sound waves.

OSCILLOSCOPES

I. An instrument which allows you to see the waves produced by sounds.

II. One old type of it is CRO ( cathode ray oscilloscope )

III. A newer type of oscilloscope is the digital oscilloscope.

LOUDNESS

I. Loudness is determined by the amplitude of the sound wave.

II. It is measured in decibels

III. The amplitude of the sound wave depends on the vibration caused by the source of the sound.

IV. The larger the vibration caused, the louder the sound will be. The smaller the vibration caused, the softer, or lower in volume, the sound will be.

The loudness values ofdifferent sounds

Sound Loudness/decibels

the sound hurts 140

a jet aircraft taking off 130

a road drill 110

a jet plane overhead 100

a noisy factory floor 90

a vacuum cleaner 80

a busy street 70

a busy department store 60

normal speech 55

voices in a town at night 40

a whisper 20

rustling leaves 10

limit of normal hearing 0

Pitch/Frequency

I. Frequency and pitch describe the same thing, but from different viewpoints.

II. While frequency measures the cycle rate of the physical waveform, pitch is how high or low it sounds when you hear it.

III. The frequency of a sound is measured in hertz (Hz).

IV. The ear of a young person is sensitive to frequencies in the range 20 to 20,000 hertz..

V. More than 20,000 : Ultrasound

VI. Less than 20 : Infrasound…..!