HW1.1 Jacob Pfister ECE301Fall2008mboutin - Rhea

MATLAB Code

%Jacob Pfister
%HW1.1

clear
clc

delta = 1/44100;
sec = 1/delta;
i = 1;

%a) Hail, Hail to old Purdue
for t = 0:delta:0.5
    y(i) = sin(2*pi*264*t);
    i = i + 1;
end
for t = (0.5 + delta):delta:0.75
    y(i) = sin(2*pi*297*t);
    i = i + 1;
end
for t = (0.75 + delta):delta:1
    y(i) = sin(2*pi*330*t);
    i = i + 1;
end
for t = (1 + delta):delta:1.5
    y(i) = sin(2*pi*352*t);
    i = i + 1;
end
for t = (1.5 + delta):delta:1.625
    y(i) = sin(2*pi*396*t);
    i = i + 1;
end
for t = (1.625 + delta):delta:1.75
    y(i) = sin(2*pi*440*t);
    i = i + 1;
end

%b) 2 Times faster

for t = (1.75 + delta):delta:2
    y(i) = sin(2*pi*264*t);
    i = i + 1;
end
for t = (2 + delta):delta:2.125
    y(i) = sin(2*pi*297*t);
    i = i + 1;
end
for t = (2.125 + delta):delta:2.5
    y(i) = sin(2*pi*330*t);
    i = i + 1;
end
for t = (2.5 + delta):delta:3
    y(i) = sin(2*pi*352*t);
    i = i + 1;
end
for t = (3 + delta):delta:3.0625
    y(i) = sin(2*pi*396*t);
    i = i + 1;
end
for t = (3.0625 + delta):delta:3.125
    y(i) = sin(2*pi*440*t);
    i = i + 1;
end

%c) y(t) = x(2t)
for t = 3.125:delta:3.625
    y(i) = sin(4*pi*264*t);
    i = i + 1;
end
for t = (3.625 + delta):delta:3.875
    y(i) = sin(4*pi*297*t);
    i = i + 1;
end
for t = (3.875 + delta):delta:4.125
    y(i) = sin(4*pi*330*t);
    i = i + 1;
end
for t = (4.125 + delta):delta:4.625
    y(i) = sin(4*pi*352*t);
    i = i + 1;
end
for t = (4.625 + delta):delta:4.75
    y(i) = sin(4*pi*396*t);
    i = i + 1;
end
for t = (4.75 + delta):delta:4.875
    y(i) = sin(4*pi*440*t);
    i = i + 1;
end

%play
sound(y,44100);

%write file
wavwrite(y,44100,32,'HailPurdueRemix.wav');

Sound File

Media:HailPurdueRemix_ECE301Fall2008mboutin.wav

Comments

I'm not sure I got the the lengths of the different notes exactly right, but it' pretty close. The transformation y(t) = x(2t) doubles the frequency, which effectively bumps the tune up an octave. This result is demonstrated in the sound file above. The crackling sound between the notes is a little annoying. I'm guessing this is because of the abrupt transitions between notes. In "real" sound, the sounds that we are used to hearing everyday, the previous note would still be reverberating as the next note was being played, so the transition would be smooth.