Sound

In physics, sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid.

In human physiology and psychology, sound is the reception of such waves and their perception by the brain.[1] Humans can only hear sound waves as distinct pitches when the frequency lies between about 20 Hz and 20 kHz. Sound waves above 20 kHz are known as ultrasound and is not perceptible by humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges.

Audio is one important element of multimedia. Which is stored in the form of digital signals that can be played back by using a program designed specifically for audio work, if the multimedia works are using sounds that are inspiring and consistent with the content in the presentation will help make the multimedia system more perfect.
Also helps create interesting things about the story because the sound influences the user more than the message or slide. Therefore, the sound is a necessary element for multimedia that can be imported via the microphone,CD,DVD,tape and radio.