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% Homework #2 - Sample Solutions
%

clear all;

% Hahaha. This loads file 'laughter.mat' into variable 'y'. 
load('laughter')
subplot(3,1,1);
plot(y)
title('Laughter - Original');

% #1
% Play sound clip backwards
sound(fliplr(y));
pause

% #2
% How many samples?
samples = length(y)

% #3
% Sub-sample by half. Two acceptable interpretations:
y_ds   = y(1:2:length(y));   % Downsampled
y_half = y(1:length(y/2));   % Sound truncated mid-way through

% #4
% Peak Amplitude and its locations
peak = max(y)
find(y==peak)

% #5
% Locations where |amplitude| > 0.8
locations  = find(abs(y) > 0.8)

% #6
% Number of times |amplitude| > 0.8
occurences = length(locations)

% #7
% Set those occurrences to 0.08
y_threshold=y;
y_threshold(locations)=0.8;

% #8
subplot(3,1,2);
plot(y_threshold)
xlabel('time'); ylabel('Amplitude');
title('Laughter w/ |amplitude| limited to 0.8');

% #9
% Cut-off the negative band. Two acceptable solutions:
y_cutoff = y; y_cutoff(find(y<0))=0;    % Cut-off
y_cutout = y >= 0;                      % Cut-out

% #10
subplot(3,1,3);
plot(y_cutoff)
xlabel('time'); ylabel('Ampliude');
title('Laughter w/ amplitudes < 0 cut-off');
sound(y_cutoff);