Sound waves carry energy through a medium without the particles of the medium traveling along.
A common medium for sound is air.
Sound is defined as a disturbance that travels through a medium as a longitudinal wave.
Production of Sound Waves
A vibrating object creates compressions and rarefactions that travel through the air as longitudinal waves.
Mechanism of Sound Production:
When a person speaks or sings, they force air from their lungs up through their voice box, also known as the larynx.
The larynx consists of two folds of tissue called vocal cords.
The forced air rushes by the vocal cords, making them vibrate.
These vibrations produce compressions and rarefactions in the air.
The air carries these longitudinal waves to other people's ears and the speaker's own ears.
Properties of Sound Waves
Diffraction of Sound Waves:
Sound waves can diffract as they pass through small spaces, similar to how water waves behave.
Due to diffraction, one can hear sounds from around corners.
Factors Affecting the Speed of Sound
The speed of sound is influenced by several factors:
Elasticity:
Defined as the ability of a material to bounce back after being disturbed.
Example: A rubber band is an elastic substance.
Sound travels more quickly in mediums with a high degree of elasticity, because the particles return to their original positions rapidly after being compressed.
Density:
Defined as the amount of matter (mass) in a given volume of space.
Sound travels more slowly in denser materials, such as metals.
Temperature:
The temperature of the medium affects the speed of sound significantly.
At 20°C (room temperature), sound travels at approximately 340 m/s.
Sound travels more slowly at lower temperatures and faster at higher temperatures.
REVISE AND REINFORCE
Factors Affecting the Speed of Sound
Factor
Change in Factor
Effect on Speed of Sound
Elasticity
Increase in elasticity
Sound travels faster
Density
Increase in density
Sound travels slower
Temperature
Decrease in temperature
Sound travels slower
Explanation of Sound Travel
Sound travels as compressions and rarefactions in a medium (e.g., air) due to the vibrations of an object, which causes surrounding particles to move and transmit the sound energy without actually moving the particles along the way.