Final exam Forth Task : Sound as Wave Essay

Have you ever thought why our ears can hear? it is because sound as waves. previously let's see what is actually wave. wave is a disturbance or vibrations that propagate. then why sound as can be described as wave? because sound is longitudianal wave, that is wave that propagate to the direction of vibrate in the direction of propagation direction. When a sound source vibrates, sound waves propagate through vibrate air molecules with the way - air molecules back and forth. Making every moment, these molecules were squeezed in some places, they produce high-pressure region, but in other places stretched, resulting in the pressure region lower. High and low pressure waves alternately moving in the air, spreading from the sound source. That's why sound waves are longitudinal waves.

The sound is one of mechanic wave and therefore we find it anywhere, as long as it is contained in the air, water or solids. But when we observe a vibrating sound source in space vacuum, then we will not hear a sound as we hear on earth .

Most of sound is a combination of various signals, but the pure sound could theoretically be explained by the speed of vibrate or frequency is measured in Hertz (Hz). The frequency of the number of wave that occur in one second. Single sound frequency regularly called tone, whereas a single sound is called irregular frequency hiss. Limit the frequency of sound that can be heard by the human ear roughly from 20 Hz to 20 kHz in common amplitude with variations in the response curve. Sounds above 20 kHz is called ultrasonic and below 20 Hz is called infrasound. Ultrasonic and infrasonic sound can not be heard by humans but some animals can hear sounds with frequencies. for example bats and dolphins can hear the ultrasonic frequency while the frequency infrasonic sound can be heard by dogs and crickets.