HW1, ECE301, Prof. Boutin

In this homework assignment, we were asked to write a Matlab code to play the "Hail Purdue" song with different speeds and pitch. Here are my results:

Sound File

• Hail Purdue

M-File

% Jun Hyeong Park 
% ECE 301 HW #1_ Playing music

for a=0:18
    f(a+1)=220*2^(a/12);
end
A=f(1);    % la
Bb=f(2);   % ti flat
B=f(3);    % ti
C=f(4);    % do
Db=f(5);   % re flat
D=f(6);    % re
Eb=f(7);   % mi flat
E=f(8);    % mi
F=f(9);    % fa
Gb=f(10);  % so flat
G=f(11);   % so
A2b=f(12); % upper la flat
A2=f(13);  % upper la
B2b=f(14); % upper ti falt
B2=f(15);  % upper ti
C2=f(16);  % upper do
D2b=f(17); % upper re flat
D2=f(18);  % upper re
E2b=f(19); % upper mi flat
M=0;       % Mute
% when I saw a music score of Hail Purdue, bpm was 140. 140bpm means
% 140 quarter notes per a minute. It means that 1 quarter note per 0.43 seconds. 
P=0.43;   % 1 quarter note
TP=P*2;   % 2 - quarter
FP=P*4;   % 1
THP=P*3;  % 3 - quarter
QP=P*1.5; % 3 - 8 
H=P/2;    % half time

notes=[Eb,F,G,A2b,G,A2b,G,A2b,G,A2b,B2b,A2b,Eb,F,G,M, ...
       G,A2b,A2,B2b,A2,B2b,A2,B2b,A2,B2b,C2,B2b,Eb,D2b,C2,M, ...
       Eb,F,G,A2b,G,A2b,G,A2b,G,A2b,E2b,C2,B2b,A2b,D2b,A2b,A2b ...
       B2b,B2b,B2,B2,C2,D2b,E2b,C2,B2b,A2b,C2,B2b, ...
       B2b, ...
       Eb,F,G,A2b,B2b,C2,C2,D2b,D2b,D2b,A2b,B2b,B2,C2, ...
       C2,C2,B2b,A2b,B2b,C2,C2,B2b,F,G,A2b,G,F,B2b, ...
       Eb,Eb,F,G,A2b,B2b,C2,C2,C2, ...
       D2b,D2b,A2b,B2b,C2,M,F,G, ...
       A2b,F,Eb,A2b,C2,Eb,C2,B2b,A2b,A2b];
   
duration=[P,P,P,P,P,P,H,H,H,H,P,P,P,P,THP,P, ...
          P,P,P,P,P,P,H,H,H,H,P,P,P,P,THP,P, ...
          P,P,P,P,P,P,H,H,H,H,P,P,P,P,THP,H,H ...
          QP,H,QP,H,QP,H,H,H,H,H,TP,TP, ...
          FP, ...
          TP,P,P,QP,H,P,P,P,H,H,P,H,H,FP, ...
          TP,P,P,QP,H,P,P,P,H,H,P,H,H,FP, ...
          QP,H,P,P,QP,H,P,H,H, ...
          P,P,P,P,THP,P,QP,H, ...
          P,P,P,P,TP,QP,H,QP,H,THP];

delta = 0.00005;
% Question #1.a
for n= 1:117                 % number of notes = 117
    t=0:delta:duration(n);   % normal speed
    x=sin(2*pi*t*notes(n));  % sine wave
    sound(x,1/delta);        % play a song
end

pause(1)
% Question #1.b

for n= 1:117
    t=0:delta:duration(n)*0.5; % becomes faster twice. 
    x=sin(2*pi*t*notes(n));    % sine wave
    sound(x,1/delta);          % I can hear a song that is played at double speed.
end

pause(1)
% Question #1.c
for n= 1:117
    t=0:delta:duration(n);     % normal speed
    y=sin(2*pi*2*t*notes(n));  % rescale y(t) = x(2t) 
    sound(y,1/delta);          % The frequencies become twice 
                               % It means an octave is raised. 
end