1. Bits and Pieces
November 6, 2007

2. Induction
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3. COMPARE
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4. Conclusion
Some microphones use induction to create an electrical signal.
Some speakers use the electrical signal to create movement using the reverse of the effect.
The result is sound going one way or the other.
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5. How is MP3 Compression Used?
(We will discuss WHAT it is in a few minutes)

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7. Sound Waves (Music, Speech or even noise) are analog in nature
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8. Digitization (Inadequate Sampling)
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9. 2 Bit Approach
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10. Better Nyquist Sampling Theorem:
if all significant frequencies of a signal are less than B
and if we sample the signal with a frequency 2B or higher,
we can exactly reconstruct the signal.
anything sampling rate less than 2B will lose information
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11. Poor Sampling
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12. Process Sample Fourier Transform Compress Store 11/26/2018
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13. REMOVE
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14. MP3 - Simple
Collect a “small” region of a musical signal which is periodic.
Take the Fourier Transform.
Remove any frequencies that we can’t hear.
Remove frequencies that mask other frequencies.
Remove soft frequency components that are drowned out by louder frequencies.
Remove frequency ranges that the brain won’t hear anyway.
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15. Digitizing
The sampling rate is usually taken to be 44 kbs. This is twice the frequency that we can hear.
The number of BITS requited for this process depends on the number of bits used to encode each volume.
I really don’t understand much about this!
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16. MP3 Save what is left In digital form. This is the MP3 file.
There is MUCH more than this in the actual process!
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