How to make a unit energy signal?

y=audioread('speech.wav');
subplot(2,3,1);
plot(y);
xlabel('Samples');
ylabel('Magnitude');
title('Original speech signal');

%adding awgn noise
x=awgn(y,5);
z=y+x;
%sound(z);
subplot(2,3,2);
plot(z);
xlabel('Samples');
ylabel('Magnitude');
title('Noise added to speech signal');

The amplitude of signal 'z' is greater than 1. I want to make it a unit enegry signal. How can i make it?

Answer 1

[Chunru]

%y=audioread('speech.wav');
y = rand(1000, 1);
subplot(2,3,1);
plot(y);
xlabel('Samples');
ylabel('Magnitude');
title('Original speech signal');
%adding awgn noise
x=awgn(y,5);
z=y+x;

% Normalize into [-1 1] (not unit energy)
z = z / max(abs(z));  

%sound(z);
subplot(2,3,2);
plot(z);
xlabel('Samples');
ylabel('Magnitude');
title('Noise added to speech signal');