Recording
Media:HailPurdue_ECE301Fall2008mboutin.ogg
Media:HailPurdueDoubleTime_ECE301Fall2008mboutin.ogg
Media:HailPurdueTwiceAsHigh_ECE301Fall2008mboutin.ogg
Matlab Code
Hail Purdue
clear
clc
%Sample rate
del=.00005;
%calculate frequencies for the notes in the range we need,
%starting with C (3 half steps below A(440Hz)
for i=3:14
freq(i-2)=220*2^(i/12);
end
%Assign notes to each calculated frequency
C=freq(1);
Df=freq(2);
D=freq(3);
Ef=freq(4);
E=freq(5);
F=freq(6);
Gf=freq(7);
G=freq(8);
Af=freq(9);
A=freq(10);
Bf=freq(11);
B=freq(12);
hC=2*C;
hDf=2*Df;
%Assign note lengths (in seconds)
whole=2;
h=whole*.5;
q=whole*.25;
dq=q*1.5;
e=whole*.125;
%Arrays of notes and their respective lengths to be played
%key of A flat
notes=[Ef,F,G,Af,Bf,hC]; %Hail, hail to old Purdue!
time=[h,q,q,dq,e,q];
%a) Loop through arrays of notes and times to play the song at normal
% speed
for i=1:length(notes)
t=0:del:time(i);
y=sin(2*pi*notes(i)*t);
sound(y,1/del)
pause(time(i));
end
pause(2)
%b) Play song twice as fast (done by cutting the length of the notes
% in half
for i=1:length(notes)
t=0:del:time(i)/2; %divide time by 2
y=sin(2*pi*notes(i)*t);
sound(y,1/del)
pause(time(i)/2); %also divide pause time by 2
end
pause(2)
%c) Play signal corresponding to the tune of a) and rescale
% it according to the transformation y(t)=x(2t). This plays
% the song one octave higher (by doubling the frequency)
for i=1:length(notes)
t=0:del:time(i);
y=sin(2*pi*notes(i)*t*2); % Use t*2 instead of t
sound(y,1/del)
pause(time(i));
end
