- 1 audio transmission
- 2 sound waves
- 3 audio sources
- 4 References
Sound travels through the sound waves spread in the vacuum, referred to the presence of energy transport helps to spread the sound, there are two types of waves, which are as follows: 
- Longitudinal waves: oscillate particles in the same direction as the transfer of energy, and thus oscillate the middle on positions molecules Atzanha in the direction of the spread of the wave movement, it referred to these waves consist of Tdhaguetat and Tkhalkhalat, and be in the liquid and gaseous state, consisting of a number of successive layers above the above each other, and are the longitudinal waves are the most common and simplest acoustic waves, called physics waves piezoelectricity name scientists.
- Occasional waves: solid spread by the media in the form of successive waves, which is perpendicular to the direction of the sound spread, note that water waves are a mixture of spin-off and longitudinal waves.
The sound waves are divided into three categories of different frequency bands covering each different from the other as follows: 
- Radio waves: radio waves fall within the range of the human ear's ability to hearing, and controls this type ear sound sensitivity, and Alomth them: musical instruments, human voices, or speakers.
- Sound waves under: possess waves under the audio frequencies below the audible range of, Examples include: where the elephants are using this type of waves to communicate with each other even if the distance separating them several kilometers.
- Ultrasonic sound: possess waves ultrasonic frequencies above the audible range, this type is used in medical imaging.
There are many audio sources, including: 
- Vibration solids.
- Explosions and vibrations.
- Air flow around the material leads to the formation of different frequencies, and thus the formation of sound waves, and in this way produces a sound of the flute, or whistle.
- ↑ J. S. Lamancusa (2000), NOISE CONTROL, Penn State: Hammond , Page 5.2. Edited.
- ↑ Raymond A. Serway, John W. Jewett (2004), Physics for Scientists and Engineers, U.S: Thomson Brooks, Page 513. Edited.
- ↑ "The Nature Of Sound", physics.info, Retrieved 15-10-2017. Edited.
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