Try this:
clc;
close all;
fontSize = 22;
% Load sound file.
load handel.mat;
hfile= 'handel.wav';
% Plot original signal.
sound(y);
subplot(4,1,1);
plot(y);
grid on;
title('Original Wave File', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Write out wave to a file.
wavwrite(y, Fs, hfile);
promptMessage = sprintf('Wait until the sound finishes.\nDo you want to Continue processing,\nor Cancel processing?');
titleBarCaption = 'Continue?';
button = questdlg(promptMessage, titleBarCaption, 'Continue', 'Cancel', 'Continue');
if strcmpi(button, 'Cancel')
return;
end
% Read it back in.
nsamples= 2.5*Fs;
[t,Fs]= wavread(hfile, nsamples);
% Construct attenuated portion next to original portion
v= [ t'/5 t'];
subplot(4,1,2);
plot(v);
title('Two Choruses', 'FontSize', fontSize);
grid on;
sound(v);
promptMessage = sprintf('Wait until the sound finishes.\nDo you want to Continue processing,\nor Cancel processing?');
titleBarCaption = 'Continue?';
button = questdlg(promptMessage, titleBarCaption, 'Continue', 'Cancel', 'Continue');
if strcmpi(button, 'Cancel')
return;
end
% Construct ramps
amplitudeEnvelope = [linspace(0, 1, length(t)), linspace(1, 0, length(t))];
subplot(4,1,3);
plot(amplitudeEnvelope);
grid on;
title('Amplitude Ramp', 'FontSize', fontSize);
% ------ MAIN PART OF THE PROGRAM --------
% Multiply the amplitude envelope by the original waveform
% to produce the signal where the volume ramps up then down.
wave2 = [t' t'] .* amplitudeEnvelope;
%-------------------------------------------
subplot(4,1,4);
plot(wave2);
grid on;
sound(wave2);
title('Ramped Sound', 'FontSize', fontSize);
