By ROZAKI BIN PAIJAN
1.8 Sound and Hearing
Properties of Sound
- Sound is produced by vibrations.
- Sound cannot travel in vacuum.
- Sound requires a medium to travel solid, liquid and gas. - Sound can be reflected and refracted. - Sound travels fastest in solids, followed by liquid and slowest in gases. - The speed of sound in air is approximately 340m/s.
Reflection and Absorption of Sound
- Reflected sounds are called echoes - Hard and smooth surfaces are good reflectors of sound Example : Planks, walls
- Soft and rough surfaces are good absorbers of sound Example : Curtains, towel
Application of Reflection and Absorption of Sound
A recording studio is covered with soft materials to reduce echo. Echoes would spoil the quality of the recording.
GROUP DISCUSSION
WHAT IS THE IMPORTANCE OF SOUND????????????????????
Defects of Hearing and Ways to Correct Them
1. Involves the outer and middle ear
Examples : Wax blockage, punctured eardrum, birth defects or ear infections Ways to correct them : Treated medically or corrected surgically
Defects of Hearing and Ways to Correct Them
2. Damages to the inner ear
Examples : Process of aging, bacterial infections, a severe blow to the side of the head, extended exposure to loud sound or tumour in the inner ear Ways to correct them : Using hearing aids
Stereophonic Hearing
Stereophonic hearing is hearing sounds from our surroundings with two ears. This type of hearing enables us to distinguish the direction of sound.
The ear closer to the source of sound detects the sound slightly earlier and louder.
We will be able to determine the location of the source of the sound after the brain interprets the differences.
STEREOPONIC HEARING