Hello,
         Please find
the answer attached as under. Please give a thumbs up
rating if you find the answer useful! Have a rocking day
ahead!
NOTE: i do not have access to your recorded voice sample, hence
I have written the code for a stored sample:
************ Matlab Code ************
load handel;
%to add an echo after 1s (with amplitude=0.5, phase=pi/3.5)
echo_vector=[1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
zeros(1,Fs)Â Â Â Â ...
           Â
0.5*exp(1i*pi/3.5) zeros(1,1.5*Fs) ...
           Â
0.5*exp(1i*1.2*pi)Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
];
yecho=real(conv(y,echo_vector));
sound(yecho,Fs);
*********** End of Code *****************
*****************************************************************
PS: Please do not forget the thumbs
up!