Test it on different sound data, and summarize your observations.

Try modifying the MATH equation, swap coefficients, and summarize your observations.

u = audioread('FunkyDrums-44p1-stereo-25secs.mp3');

% average RIGHT and LEFT channel data for MONO sound

u = (u(:,1) + u(:,2))/2;

plot(u);

apu = audioplayer(u,44100);

play(apu);

% sine wave example

%Ts=1e-3;

%u=sin(2*pi*3*[0:5000]*Ts);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

N=length(u);

y=zeros(N,1);

for k=2:N

y(k)=0.99*y(k-1)+0.01*u(k);

end

% for the sine wave example, comment out the next line

y=y/max(abs(y));

plot(y);

apy = audioplayer(y,44100);

play(apy);