I want to filter a .wav file in a second order low pass filtre

Question

回答： Sulaymon Eshkabilov 2021-12-28

I need to filtre, an audio filtre torought a low pass system. I have this code so far:

y=audioread('hfnoise.wav');

plot(y);

sound(y);

w_n = 2*pi*600;

Z = 2;

s = tf('s');

G = (w_n^2)/(s^2 + 2*Z*w_n*s + w_n^2);

bode(G);

u = reshape(y,[1,24440]);

t=1:1:24440;

p=lsim(G,u,t);

plot(p)

The signal doesn't change by passing torought the filter. The .wav file is a double of 1x24440. The filtering must be done using lsim. Help, please!

Thank you.

Answer 1

Sulaymon Eshkabilov 2021-12-28

Note that lsim() is not a filter. It is a simulated time response of dynamic system to arbitrary inputs; simulated response data.

Here lsim () is working correctly and thus, you'd needd to employ filter() to filter out the undesired noises from your signal y.