pkg load signal

file_path = 'part1.wav';

[x, Fs] = audioread(file_path);

t = (0:length(x)-1) / Fs;



subplot(2,2,1);
plot(t, x);
title('Time Domain - Original Signal');
xlabel('Time (s)');
ylabel('Amplitude');

window = blackman(length(t));
windowed_part = x .* window;

subplot(2,2,2);
plot(t, windowed_part)
xlabel('Time (s)')
ylabel('Amplitude')
title('Blackman Window Applied')


Nfir = 5;
cutOffFrequency = 50;

[B, A] = butter(Nfir,  cutOffFrequency/(Fs/2));

filteredSignal = filter(B, A, windowed_cosine);



subplot(2,2,3);
plot(t, filteredSignal);
xlabel('time (s)'); 
ylabel('amplitude (a.u.)');
title('IIR-Filtered signal')
 
X = fft(filteredSignal);     % Compute FFT
freq = (0:N-1) * (Fs/N);      % Frequency axis

subplot(2,2,4);
stem(freq, abs(X));
title('Filtered Signal (Frequency Domain)');
xlabel('Frequency (Hz)');
ylabel('Magnitude');

Z=roots(B);
P=roots(A);
figure
zplane(Z,P);
title ('Zeros and poles of the transsamplingFreqr function');
legend('zeros','poles');
grid on;

frequencySpectrum(filteredSignal,Fs);