% Catie 
% shepardtones.m - plays the shepard tones

% adjustable parameters commented out
% max_time = 2;
% max_repeat = 3;
% A = 440;     % "base frequency"

fs = 8192;   % the sampling rate
dt = 1/fs;
t = [0:dt:max_time];

k = -2:(-2+num_harm);
m = 2^(1/12);     % semitones
% sigmasq = 1;
rep = [];

for j = 0:11
y = zeros(size(t)); % initialize the tone vector
   for i = 1:num_harm         % use each harmonic in k
       f_ij = 2^k(i)*(A*(m^j));  % the frequency of this component
       amp = exp((-1/2*sigmasq)*(log2(f_ij/A))^2);
      y = y + amp*cos(2*pi*f_ij*t);
   end;
rep = [rep y];  % append the finished tone to the tone vector
end;


rep = repmat(rep,1,max_repeat);  % repeat max_repeat times
soundsc(rep,fs);                 % play it