Use MATLAB to Draw Signal Time Domain Waveform

[y1,Fs] = audioread('test.wav');
x1 = (0 : length(y1) - 1) / Fs;
subplot(2, 1, 1);
plot(x1, y1);
axis([0 max(x1) -1 1]);
xlabel('Time / (s)');ylabel('Amplitude');
title('original audio');

[y2,Fs] = audioread('test_secret.wav');
x2 = (0 : length(y2) - 1) / Fs;
subplot(2, 1, 2);
plot(x2, y2);
axis([0 max(x2) -1 1]);
xlabel('Time / (s)');ylabel('Amplitude');
title('information hiding audio');