Sound is a form of energy produced by vibration that travels in longitudinal waves faster through solids than liquids or gases. The human ear has external, middle, and inner portions that work together to detect sound. Sound causes the eardrum and tiny bones in the middle ear to vibrate, transmitting the vibrations to the cochlea of the inner ear which transforms them into nerve impulses sent to the brain where they are interpreted. The brain also receives information from the semicircular canals of the inner ear on balance and head position.

1. SOUND AND
HEARING

2. FACTS
● Sound is a form of energy produced by
vibration.
● Sound travels in longitudinal waves.
● Sound travels faster through solids than
liquids,gases.

3. SOUND
● Frequencies above 20,000 Hertz is
called ultrasound..
● Frequencies below 20 Hertz is called
infrasound.

4. PITCH AND FREQUENCY
COMPRESSION:where molecules are
compressed.
RAREFACTION:where molecules are spread
out.

5. VIBRATION
Repeated backward and forward.

6. WAVELENGTH and
FREQUENCY
Wavelength is the distance between one
part of a wave than another.
Frequency is the number of vibration in a
second.
=>Frequency is measured in hertz.

7. THE HUMAN EAR

8. FUNCTION OF HUMAN EAR
The ear has external, middle, and inner portions. The outer ear is called the
pinna and is made of ridged cartilage covered by skin. Sound funnels through
the pinna into the external auditory canal, a short tube that ends at the eardrum
(tympanic membrane).
Sound causes the eardrum and its tiny attached bones in the middle portion of
the ear to vibrate, and the vibrations are conducted to the nearby cochlea. The
spiral-shaped cochlea is part of the inner ear; it transforms sound into nerve
impulses that travel to the brain.
The fluid-filled semicircular canals (labyrinth) attach to the cochlea and nerves
in the inner ear. They send information on balance and head position to the
brain. The eustachian (auditory) tube drains fluid from the middle ear into the
throat (pharynx) behind the nose.

9. AMPLITUDE
Amplitude is the objective measurement of the degree of change (positive or
negative) in atmospheric pressure (the compression and rarefaction of air
molecules) caused by sound waves.
=>Measured in decibels.

10. loudness of some sounds!!!

11. REFERENCES
BOOK
INTERNET.
MADE BY MUSHK AZIZ
CLASS:VIII-B