SOME SIMPLE MANIPULATIONS OF SOUND USING DIGITAL SIGNAL PROCESSING

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SOME SIMPLE MANIPULATIONS OF SOUND USING DIGITAL
SIGNAL PROCESSING

• Richard M. Stern
• 18-791 demo
• August 31, 2004
• Department of Electrical and Computer Engineering
• and School of Computer Science
• Carnegie Mellon University
• Pittsburgh, Pennsylvania 15213

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The original sound and its spectrogram
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Downsampling the waveform

• Downsampling the waveform by factor of 2

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Consequences of downsampling

• Downsample

Original
Downsampled
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Upsampling the waveform

• Upsampling by a factor of 2

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Consequences of upsampling
Original
Upsampled
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Linear filtering the waveform
yn
xn
Filter 1 yn 3.6yn15.0yn23.2yn3.82
yn4 .013xn.032xn1.044xn2.033xn3
.013xn4 Filter 2 yn 2.7yn13.3yn22
.0yn3.57yn4 .35xn1.3xn12.0xn21.3
xn3.35xn4
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Filter 1 in the time domain
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Output of Filter 1 in the frequency domain
Original
Lowpass
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Filter 2 in the time domain
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Output of Filter 2 in the frequency domain
Original
Highpass
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The source-filter model of speech

• A useful model for representing the generation of
  speech sounds

Amplitude
pn
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Separating the vocal-tract excitation from the
filter

• Original speech
• Speech with 75-Hz excitation
• Speech with 150-Hz excitation
• Speech with noise excitation

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