noise = randn(1,8000);
sound(noise,16000)

A = [.99*exp(j*pi/8)  .99*exp(-j*pi/8)];
a = poly(A);
B = [1 -1];
b = poly(B);
y =filter(b,a,noise);

sound(y,16000)

A = [.99*exp(j*pi/4)  .99*exp(-j*pi/4)];
a = poly(A);
y =filter(b,a,noise);

sound(y,16000)