Basic Principles of Sound

Sound is a form of energy that always requires a medium to propagate. Sound is a vibration that propagates as a typically audible mechanical wave of pressure and displacement, through a medium such as air, water or materials. Speed of souund depends on the medium that the waves pass through, and is a fundamental property of the material

In physiology and psychology, sound is the reception of such waves and their perception by the brain.

Basic principles of Sound are :

1. Sound is produced by a vibrating body and travels in the form of a wave.
   
   
   
   
2. Sound waves travel through materials by vibrating the particles that make up the material.
   
   
   
   
3. The pitch of the sound is determined by the frequency of the wave (vibrations or cycles completed in a certain period of time).
   
   
   
   
   
   
   
4. Ultrasound is sound with a pitch too high to be detected by the human ear.
5. The measurement of sound waves from crest to crest determines its wavelength (λ).
   
   
   
   
6. The time is takes a sound wave to travel a distance of one complete wavelength is the same amount of time it takes the source to execute one complete vibration.
7. The sound wavelength is inversely proportional to its frequency. (λ = 1/f)
   
   Several wave modes of vibration are used in ultrasonic inspection. The most common are longitudinal, shear, and Rayleigh (surface) waves.
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9. Ultrasonic waves are very similar to light waves in that they can be reflected, refracted, and focused.
   
   
   
   
10. Reflection and refraction occurs when sound waves interact with interfaces of differing acoustic properties.  
11. In solid materials, the vibrational energy can be split into different wave modes when the wave encounters an interface at an angle other than 90 degrees.
    
    
12. Ultrasonic reflections from the presence of discontinuities or geometric features enables detection and location. 
13. The velocity of sound in a given material is constant and can only be altered by a change in the mode of energy.

References :
https://en.wikipedia.org/wiki/Sound
www.ndt-ed.org
www.asnt.org

Related blogs :

http://techshoreinspections.blogspot.com/2017/01/Techshore-Inspection-Services-ndt-ultrasonic-testing.html
http://techshoreinspections.blogspot.com/2016/12/Techshore-Inspection-Services-liquid-penetrant-test.html
http://techshoreinspections.blogspot.com/2016/10/ultrasound-testing-techniques-contact.html
http://techshoreinspections.blogspot.com/2016/10/ultrasound-testing-technique-through.html
http://techshoreinspections.blogspot.com/2016/10/ultrasound-testing-techniques-pulse.html
http://techshoreinspections.blogspot.com/2016/10/ultrasonic-testing-techniques.html
http://techshoreinspections.blogspot.com/2016/10/ultrasound-generation-principles-of.html
http://techshoreinspections.blogspot.com/2016/10/ndt-ultrasonic-testing-beam-explained.html
http://techshoreinspections.blogspot.com/2016/10/introduction-to-ndt-non-destructive.html
http://techshoreinspections.blogspot.com/2016/09/techshore-non-destructive-testing-ndt.html
http://techshoreinspections.blogspot.com/2016/09/techshore-inspection-services-explains_6.html

Documents : 

https://www.slideshare.net/techshoreinspectionservices/civil-engineering-process-of-well-treatment-techshore
https://www.slideshare.net/techshoreinspectionservices/ndt-ultrasonic-testing-techshore
https://www.slideshare.net/techshoreinspectionservices/ndt-liquid-penetration-test-techshore

Additional references:
https://www.youtube.com/channel/UCfufdF0-Hs3sLu1IX52ZJYA/videos
http://techshore.in/blog
http://techshore-updates.blogspot.in/
https://techshore-inspection-services.blogspot.in/
https://techshoreinspectionservices.blogspot.in/
https://techshoreinspections.blogspot.in/


You Tube Tutorials :
https://www.youtube.com/watch?v=bfW1eL0aTlU
https://www.youtube.com/watch?v=URlwZ3R94u8
https://www.youtube.com/watch?v=6w9Cl58-p34
https://www.youtube.com/watch?v=ZVnsx5VC77g
https://www.youtube.com/watch?v=3ZD4je9Fbn8