47 lines
1.0 KiB
Matlab
47 lines
1.0 KiB
Matlab
clear all
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close all
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clc
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[y, fs] = audioread("sound/modulator22.wav");
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ranges = [17000, 20000; 29000, 37000; 41000, 46000];
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one = y(ranges(1,1):ranges(1,2));
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two = y(ranges(2,1):ranges(2,2));
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three = y(ranges(3,1):ranges(3,2));
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word = one;
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n = length(word);
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f = (0:n-1)*(fs/n);
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f1 = 0;%Hz
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f2 = 4000;%Hz
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idx = find(f >= f1 & f <= f2); %define the index of the freq range
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f = f(idx);
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y = fft(word, n);% compute DFT of input signal
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power = abs(y).^2/n;
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power = power(idx);
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[val, ind] = max(power);
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%lowpass for the formant
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Fc = 2000; % define the cutoff frequency of the low-pass filter
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[b, a] = butter(6, Fc/(fs/2), 'low'); % design a 4th-order Butterworth low-pass filter
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Pxx_filt = filter(b, a, power); % apply the filter to the power spectrum
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length(Pxx_filt)
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length(f)
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figure;
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subplot(1,2,1) % time plot
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plot(0:1/fs:(length(word)-1)/fs,word);
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xlabel('Time (s)');
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ylabel('Amplitude (a.u.)');
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subplot(1,2,2) % freq range plot
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plot(f,10*log10(power/power(ind))); hold on;
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plot(f, 10*log10(Pxx_filt), 'r');
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xlabel('Frequency (Hz)')
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ylabel('Power (dB)')
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