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Here is a Matlab script reflecting Lecture 1.  The script plays various audio signals. Copy and paste the script into an m-file and play:
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[[Lecture 1]]
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load handel; %Loads 2 variables, y and Fs.  y is a signal containing
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information: a vector of numbers representing an audio clip.  Fs is the
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sampling frequency.
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sound(y,Fs); %play the audio file at the appropriate sampling frequency.
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input('Press enter to hear the same audio with 1/4 the samples')
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downsample = 4; %factor to decrease sampling rate by
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sound(y(1:downsample:end)*downsample,Fs/downsample); %Plays the same signal with only
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1/4 of the original "information." Note the degradation in quality
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input('Press enter to hear the same audio with 1/100 of the original samples')
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downsample = 100; %factor to decrease sampling rate by
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sound(y(1:downsample:end)*downsample,Fs/downsample); %Plays the same signal with only
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1/100 of the original "information." Original audio is nearly unrecognizable.
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input('Press enter to hear a constant tone note A')
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delta = 0.00005; %Sampling period
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t = 1:delta:3; %a vector representing 3 seconds of time
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x = sin(2*pi*440*t); %a vector representing the sinusoid tone A
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sound(x,1/delta);
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input('Press enter to hear a tone note A an octave higher')
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x = sin(2*pi*880*t); %a vector representing the sinusoid tone A an octave higher
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sound(x,1/delta);
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Revision as of 06:43, 15 June 2009

Lecture 1

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Alumni Liaison

Correspondence Chess Grandmaster and Purdue Alumni

Prof. Dan Fleetwood