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14 Cards in this Set
- Front
- Back
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What is sound?
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variations in air pressure which cause vibrations in the inner ear (ripples)
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What is an AC current?
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A "push and pull" action like waves or vibrating string or electricity.
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What are the two basic properties of sound?
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(1) loudness or volume
-----sound pressure level usually measured in decibels (2) frequency or pitch -----speed of sound waves usually measured in Hertz |
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How did acoustic recording work?
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--sound pressure caused the mechanism to move
--stylus etched a squiggly waveform on the record medium --stylus played back the results |
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How does an electrical recording work?
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--electricity could be used to move sound
--better suited to record a more accurate picture of the waveform --the microphone emerged as a very significant technology |
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What was magnetic tape? How was it developed?
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--wire recorders developed it in the Bell Labs in NY in the 1930s
--magnetophone developed in Germany during WWII --offered significant improvements to recording quality --allowed performers to correct performances using splicing and editing |
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Who developed the multi track tape recorder and what did it do?
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--Les Paul
--popular music was revolutionized |
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When did digital audio theory originate?
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in the 1930s--the Shannon Nyquist Theorum
----which involved "sampling" which is the process of converting a signal into a numeric sequence |
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What happened in the late 1970s?
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--The Japanese commercialized digital audio.
--large companies like Sony started to experiment with digital recording |
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What happened in 1982?
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The compact disc standard was proposed and formalized by Sony/Philips.
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What happened in 1984?
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Japanese companies began to develop multi track digital tape machines.
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Describe the process going from analog to digital.
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1--the electrical signal travels from the microphone to an A/D converter
2--the converter takes "snapshots" or samples of the volume level (bit rate) at even intervals (sampling rate) 3--the samples are stored to a hard drive or tape as 0s and 1s (binary code) 4--once the signal is represented by a stream of numbers, it can be easily manipulated with mathematical algorithms |
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What must happen with the sampling rate and the bit rate?
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The sampling rate must be at least twice the highest frequency you want to record.
The bit rate. Digital recordings below 16 bit (CD quality) are audibly inferior and have noticeable noise. |
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What are some advantages and disadvantages associated with digital audio?
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advantages:
--you can hear the same sound quality as the musician in the studio --you can access music instantaneously disadvantages: --you can make identical copies --you can edit and manipulate the audio easily --you can disseminate music exponentially |
