Sound by 2E1 Ebel

SOUND
[A]Sound is a form of energy and is caused by objects vibrating .

[B]Sound travels through air as vibrations .When a loudspeaker produce a sound , the vibration of the skin of the speaker causes the surrounding air molecules to also vibrate . These vibration spread outwards , passing on the sound energy until it reaches the ears.

[C]Sound takes time to travel from one place to the other. Sound travels at a speed of 330m/s in air .This is much slower than the speed of light [300 000 000m/s]Thats why you will always see the flash of lighting followed by the crack of thunder .

[D]Sound cannot travel through a vacuum[empty space] it needs a medium[substance] to travel through .Sound can travel through gases , liquid and solids. It travels through liquid and solids faster than gases as the particles of solid and liquids are closer , so the vibration pass more easily .However , the energy of the sound is soon used up passing through liquids and solids .

[E]Sound are all around us and provide a means of communication [talking , whistling and singing ] give us warning signals [alarms , telephones , fire bells , police sirens] give us pleasure [music , singing ]

[F]However some sound are unnecessary , they are describes as noise [ traffic noise , loud music , aircraft noise , building sites noise , drilling noise ]. Sound levels are measured as decibels[dB].The loudest sound , which causes pain is called the threshold of pain.

[G]The ear is the natural detector of sound . The external ear is like a funnel to channel the sound waves towards the ear drum .This then starts to vibrate and the bones in the middle ear amplify this vibration which causes waves in the liquid inside the inner ear. These waves produce electrical pulses in the nerve cells which are carried by the auditory nerve to the brain intercepts these electrical signs as sounds

Biobliography:Science Keynotes -Christopher N. Prescott