Sound is a form of energy.we can hear anywhere different types of sounds ..while we are traveling in train , buses, bikes,etc..in nature birds will also produce some sound, before raining sound of thunder produce in monsoon..& the rain falling will generate sound ..sound will produce when object moves to & fro motion it will vibrate. For example: when we hold the speaker of transistor we feel vibrate..radio & television also in the same way vibrate.
Oscillation: vibration is repeated to & fro motion
Amplitude: the object moves from central position to extreme position from respective sides. When an object moves from one extreme position to other extreme position & come back its to the original position i.e..one complete oscillation
Time period: time taken to complete one oscillation
Frequency: no of oscillations per second.units: hertz
When an object takes 20 oscillations its frequency 20 hertz.
Due to vibrations sound is produced.loudness of sound based on Amplitude of vibration. When the amplitude of vibrating air molecules is large, the sound is loud. Whether a sound is high or low pitch based on the frequency of vibration .if frequency of vibration is high ..sound will produce high pitch
If the amplitude is too small. our ears cannot hear sound in the same way..if the frequency is less than 20 hertz cannot hear nor can our ears hear the sound if frequency greater than 20,000 hertz is ultrasonic.human voice can produce sound with a frequency between 60 Hertz & 13,000 hertz
Some animals can also produce ultrasonic sounds.ex: bat
Ex.dogs, leopards, deer hear an ultrasonic sound.
Ears are sensory organs that help in hearing.
Mechanism of hearing sound. a sound from the outside- outer ear- eardrum-middle ear.
The sound strikes the eardrum , drum vibrates to & fro .auditory nerve signal ..takes motion signal to the brain
Very important to note: damage of the drum leads to a deaf person
Medium is required for sound to travel .ex: solids, liquids & gases…but not in a vacuum
Sound takes time to travel from vibrating objects to our ears.
Speed of sound depends on the medium.
In dry air, the velocity of sound is 330 meters per second.
Velocity in water is 1500 m/s