# Physics Course/Types of Waves/Sound Waves

## Sound Wave

Sound wave is a Longitudinal Wave. When Sound Wave travels through air it will create expanding or shrinking column of airs called Rarefraction and RareExpansion.

Sound Wave | || | ||

## Sound Wave Characteristics

1. Sound does not exist in vacuum .
2. Sound wave requires medium of matter to spread itself . Sound wave travels through any medium Solid , Liquid , Gas
3. The speed of Sound wave varies with Pressure and Temperature of the medium . Sound wave travels at a speed v = λ f . At Standard Pressure & Temperature in air the speed is calculated equal to v = 333 m/s
4. Sound Wave that is audible to human ear is in the frequency range 20Hz - 20KHz .

## Sound's Effects

When Sound wave travel through a medium if there is a blocking object that has a height greater than the wavelength of sound wave . Sound wave will suffer from the following effects

### Reflection

Sound wave being reflected back to the medium it comes from and can create interference with other wave in the medium

### Refraction

Only part of Sound wave is passing through . Sound does not reach its destination

### Diffraction

Wave travels through narrow opens

### Interference

When two sound waves travel toward each other will interfere either Constructively or Destructively to produce different sound interferences like Noise, Echoe, Intermittent, No sound

## Applications

### Tele Communication

In Tele Communication, in order to carry Sound wave over a long distance sound wave must be mixed with a high frequency carrier wave in a process called Modulation .

In Radio Communication, There are 3 modulations methods are used in mixing Sound wave and Carrier wave namely AM - Amplitude Modulation, FM - Frequency Modulation, PM - Phase Modulation.

In analog electronics , AM and FM is widely used . In digital electronic, PM is used

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