(Replacing page with 'Question 1: MATLAB code: Media:Example.ogg Sound file: Media:Example.ogg')
 
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Question 1:  
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% Question 1:
MATLAB code: [[Media:Example.ogg]]
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function[] = question1()
Sound file:  [[Media:Example.ogg]]
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N1 = sin(2*pi*391.995436*[0:0.0001:1]);        %G quarter note
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N2 = sin(2*pi*466.1637615*[0:0.0001:1]);        %Bflat quarter
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N3 = sin(2*pi*523.2511306*[0:0.0001:1.5]);      %C dotted quarter
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N4 = sin(2*pi*391.995436*[0:0.0001:1]);        %G quarter
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N5 = sin(2*pi*466.1637615*[0:0.0001:1]);        %Bflat quarter
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N6 = sin(2*pi*554.3652618*[0:0.0001:0.5]);      %Csharp eigth
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N7 = sin(2*pi*523.2511306*[0:0.0001:2]);        %C half
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rest = [0:0.0001:2.5];                        %rest half and an eigth
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% smoke on the water (part a):
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tune = [N1 N2 N3 N4 N5 N6 N7 N1 N2 N3 N2 N1 rest];
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wavwrite(0.02*tune, 18667, 'question1a.wav');
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% twice as fast (part b):
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wavwrite(0.02*tune, 37333, 'question1b.wav');
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% y(t) = x(2t)  (part c):
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newtune = [1:1:(length(tune)/2)];
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for i=1:(length(tune)/2)
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    newtune(1,i) = tune(1,2*i);
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end
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wavwrite(0.02*newtune, 18667, 'question1c.wav');
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Sound files:  [[Media:question1a.wav]]
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              [[Media:question1b.wav]]
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              [[Media:question1c.wav]]
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% Question 2:
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function[] = question2()
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[y, Fs] = wavread('Beatles.wav');
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y = flipud(y);
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wavwrite(y, Fs, 'question2.wav');
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Sound file:  [[Media:question2.wav]]
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1. The repeated phrase was "number nine".
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2. I couldn't hear any message in the reversed version.

Latest revision as of 19:18, 14 January 2011

% Question 1:
function[] = question1()
N1 = sin(2*pi*391.995436*[0:0.0001:1]);         %G quarter note
N2 = sin(2*pi*466.1637615*[0:0.0001:1]);        %Bflat quarter
N3 = sin(2*pi*523.2511306*[0:0.0001:1.5]);      %C dotted quarter
N4 = sin(2*pi*391.995436*[0:0.0001:1]);         %G quarter
N5 = sin(2*pi*466.1637615*[0:0.0001:1]);        %Bflat quarter
N6 = sin(2*pi*554.3652618*[0:0.0001:0.5]);      %Csharp eigth
N7 = sin(2*pi*523.2511306*[0:0.0001:2]);        %C half
rest = [0:0.0001:2.5];                         %rest half and an eigth
% smoke on the water (part a):
tune = [N1 N2 N3 N4 N5 N6 N7 N1 N2 N3 N2 N1 rest];
wavwrite(0.02*tune, 18667, 'question1a.wav'); 

% twice as fast (part b):
wavwrite(0.02*tune, 37333, 'question1b.wav');
% y(t) = x(2t)  (part c):
newtune = [1:1:(length(tune)/2)];
for i=1:(length(tune)/2)
    newtune(1,i) = tune(1,2*i);
end
wavwrite(0.02*newtune, 18667, 'question1c.wav');


Sound files:  Media:question1a.wav
              Media:question1b.wav
              Media:question1c.wav



% Question 2:
function[] = question2()
[y, Fs] = wavread('Beatles.wav');
y = flipud(y);
wavwrite(y, Fs, 'question2.wav');


Sound file:  Media:question2.wav
1. The repeated phrase was "number nine".
2. I couldn't hear any message in the reversed version.

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Ph.D. 2007, working on developing cool imaging technologies for digital cameras, camera phones, and video surveillance cameras.

Buyue Zhang