Ch. 6 - Digital Audio - 2/15/2010 CIS 3003 Fundamentals of...

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2/15/2010 1 CIS 3003 Fundamentals of Information Technology 1 Information Technology in Theory By Pelin Aksoy and Laura DeNardis Chapter 6 Digital Audio Technology CIS 3003 Fundamentals of Information Technology 2 Objectives ± Understand the physical and mathematical basis of sound waves ± Recognize the amplitude, frequency, and phase properties of sound ± Apply the three-step process for audio digitization ± Understand and apply the Nyquist Sampling 2 Theorem Information Technology in Theory
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2/15/2010 2 CIS 3003 Fundamentals of Information Technology 3 Objectives (continued) ± Recognize the need for digital audio compression ± Explain how music files can be compressed without significant sound quality degradation ± Understand the difference between lossy and lossless compression techniques B f ili ith l di it l di f t 3 ± Become familiar with popular digital audio formats like MP3, WMA, WAV, AAC, and AIFF Information Technology in Theory CIS 3003 Fundamentals of Information Technology 4 Recording Sound ± The phonograph, invented by Thomas Edison in the late 1800s, was the first device created for sound recording and lbk playback ± The tin-coated cylinders of the early phonograph were ultimately replaced by vinyl records ± Another early analog recording technique from the late 1800s relied on magnetism and electricity ± The magnetic recording approach was adopted by the music industry, and magnetic tapes replaced metallic wires as a di di 4 recording medium ± This type of recording technique was later used to store music on audiocassettes, but its popularity diminished in the wake of CDs, flash drives, and alternative storage media Information Technology in Theory
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2/15/2010 3 CIS 3003 Fundamentals of Information Technology 5 Recording Sound (continued) 5 Information Technology in Theory CIS 3003 Fundamentals of Information Technology 6 Creating Sound ± Sound is caused by physical disturbances of air Sound is caused by physical disturbances of air molecules ± This transfer of energy among molecules creates a mechanical wave of energy called a sound wave , which propagates away from the source of the disturbance 6 ± The creation of sound waves is usually compared to the formation of water waves Information Technology in Theory
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2/15/2010 4 CIS 3003 Fundamentals of Information Technology 7 Creating Sound (continued) 7 Information Technology in Theory CIS 3003 Fundamentals of Information Technology 8 Converting Between Sound and Electricity ± To digitize sound, electrical systems must convert mechanical sound waves into electrical sound mechanical sound waves into electrical sound waves —in other words, into an electrical audio signal ± Microphones capture sound waves and convert them into an electrical form, while speakers convert the electrical signal back into sound wave 8 electrical signal back into sound waves ± The electrical fluctuations correspond to the pressure fluctuations of the sound wave Information Technology in Theory
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2/15/2010 5 CIS 3003 Fundamentals of Information Technology 9
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This note was uploaded on 10/05/2010 for the course CIS CIS 3003 taught by Professor K during the Spring '10 term at University of Central Florida.

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Ch. 6 - Digital Audio - 2/15/2010 CIS 3003 Fundamentals of...

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