lab9

function [V] = audioeq(inputPath, outputPath, Q)

[Y, FS] = audioread(inputPath);

Z = Y;

freqC1 = 60; % Hz
freqC2 = 230;
freqC3 = 910;
freqC4 = 4000;
freqC5 = 14000;

freqL1 = freqC1 * ( (-1) / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));
freqL2 = freqC2 * ( (-1) / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));
freqL3 = freqC3 * ( (-1) / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));
freqL4 = freqC4 * ( (-1) / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));
freqL5 = freqC5 * ( (-1) / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));

freqU1 = freqC1 * ( 1 / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));
freqU2 = freqC2 * ( 1 / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));
freqU3 = freqC3 * ( 1 / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));
freqU4 = freqC4 * ( 1 / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));
freqU5 = freqC5 * ( 1 / (2 * Q) + sqrt(1 + (1 / 4 * Q ^ 2)));

normFL1 = freqL1 / (FS / 2);
normFL2 = freqL2 / (FS / 2);
normFL3 = freqL3 / (FS / 2);
normFL4 = freqL4 / (FS / 2);
normFL5 = freqL5 / (FS / 2);

normFU1 = freqU1 / (FS / 2);
normFU2 = freqU2 / (FS / 2);
normFU3 = freqU3 / (FS / 2);
normFU4 = freqU4 / (FS / 2);
normFU5 = freqU5 / (FS / 2);

bw1 = freqC1 / Q;
bw2 = freqC2 / Q;
bw3 = freqC3 / Q;
bw4 = freqC4 / Q;
bw5 = freqC5 / Q;

nOrder = 40;

[filt1Num, filt1Den] = fir1(nOrder, normFU1, 'low');
[filt2Num, filt2Den] = fir1(nOrder, [normFL2 normFU2], 'bandpass');
[filt3Num, filt3Den] = fir1(nOrder, [normFL3 normFU3], 'bandpass');
[filt4Num, filt4Den] = fir1(nOrder, [normFL4 normFU4], 'bandpass');
[filt5Num, filt5Den] = fir1(nOrder, normFL5, 'high');

[H1, W1] = freqz(filt1Num, filt1Den);
[H2, W2] = freqz(filt2Num, filt2Den);
[H3, W3] = freqz(filt3Num, filt3Den);
[H4, W4] = freqz(filt4Num, filt4Den);
[H5, W5] = freqz(filt5Num, filt5Den);

figure;
plot(W1 / pi, abs(H1), W2 / pi, abs(H2), W3 / pi, abs(H3), W4 / pi, abs(H4), W5 / pi, abs(H5));
xlabel('Normalized Frequency');
ylabel('Magnitude');
title('Frequency response of invidual filters');

sumH = abs(H1) + abs(H2) + abs(H3) + abs(H4) + abs(H5);
figure;
plot(W1 / pi, 20 * log10(sumH));
xlabel('Normalized Frequency');
ylabel('20 log10(Mag)');
title('Frequency response of sum of filters');

audiowrite(outputPath, Z, FS);

end