function miniSynth(Name,Freq,Amp)
% simple waves synth
% Gavin Bell
% Science of Music IL016
% January 2016
%
% Name is full filename e.g. 'miniSynth_1.wav'
% Freq is list of frquencies starting with fundamental
% e.g. [440 880 2750]
% Amp is amplitudes of those frequencies
% e.g. [1 0.2 0.1]
%---basic parameters
Fs = 32768;                         % sample rate
Dur = 5;                            % duration in s
Vol = 0.8;                          % volume
Tcyc = 1/Freq(1);                   % time for 1 cycle
Ncyc = round(Fs*Tcyc);              % number of samples in 1 cycle
plotCyc = 5;                        % number of cycles to plot
%
t = linspace(1/Fs, Dur, Dur*Fs);    % time
y = zeros(1,Dur*Fs);                % initialize sound data
for j=1:length(Freq);               % loop to add up frequencies
  y = y + Amp(j)*sin(2*pi*Freq(j)*t);
end
y = Vol*y/max(y);                   % normalize to Vol 
audiowrite(Name,y,Fs);              % write WAV file
%
yPlot = y(1:Ncyc*plotCyc);          % plot plotCyc cycles to see beats
tPlot = t(1:Ncyc*plotCyc);
subplot(2,1,1), plot(tPlot,yPlot), xlabel('time (s)')
Y = abs(fft(y));                    % FFT of y for plot
P = Y(1:(Fs*Dur/2)+1)/(Fs*Dur);     % scale power (?)
f = (1:(Fs*Dur/2)+1)/Dur;           % frequency
subplot(2,1,2), plot(f,P), axis([0 max(f) 0 max(P)*1.1]), xlabel('frequency (Hz)')