%
% Example of tonal disconsonance and "beats"
%
duration = 30.0;
sampling_freq = 8192; delta_t=1/sampling_freq;

t = 0 : delta_t : duration;
% The following is a 300 Hz harmonic, which is 'shaped' by 
%   2 Hz envelope. Modify both frequencies.

 signal = sin( 2*pi*300*t).*sin(2*pi*2*t);   

% This is the same as the signal 
%       signal = .5*(cos( 2*pi*298*t)-cos(2*pi*302*t)); 


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% uncomment the following for nonstationary instantaneous phase %%%
%%  (be sure to comment out the earlier defn of 'signal'         %%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%  signal = sin( 2*pi*300*t).*sin(2*pi*2*t.^2.5);   

sound(signal, sampling_freq)
plot(t, signal)          
%
axis([0, 0.4, -1, 1]) 
% Estimate the frequency of the tone from the graph.
% For the nonstationary signal, use various axes to 
% observe the values of the local frequency