Question

Need explanation of MATLAB code which creates echo. (SIGNAL PROCESSING)

If the original audio signal is x(t) then the echo is y(t) = x(t) + alpha*x(t-delay)

This code below creates this echo however I don't understand how every line of the code works, could someone comment this code so I can understand?

[x,Fs] = audioread('Hallelujah.wav');  
 sound(x,Fs);   
 delay = 0.5; % 0.5s delay  
 alpha = 0.65; % echo strength  
 D = delay*Fs;  
 y = zeros(size(x));  
 y(1:D) = x(1:D);  
   
 for i=D+1:length(x)  
   y(i) = x(i) + alpha*x(i-D);  
 end  

Answer 1

desired graph