254 lines
6.6 KiB
Matlab
254 lines
6.6 KiB
Matlab
%% lpss.m
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%%
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%% Coursework script
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close all;clear all;clc;
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NAME = 'hood_m';
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% NAME = 'head_f';
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SEGMENT_LENGTH = 100; % ms
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SEGMENT_OFFSET = 20; % ms from start
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LPC_ORDER = 30;
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AC_DISP_SAMPLES = 1000; % autocorrelation display samples
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WINDOW_NUMBER = 10; % number of windows for spectrogram
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WINDOW_OVERLAP = 10; % ms
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SYNTH_WINDOW_NUMBER = 60; % number of windows for spectrogram
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SYNTH_WINDOW_OVERLAP = 20; % ms
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PREEMPHASIS_COEFFS = [1 -0.9]; % first order zero coeff for pre-emphasis
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F0 = 60; % low-pitched male speech
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% F0 = 600; % children
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% flags for selective running
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PREEMPHASIS = false;
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CEPSTRUM_LOW_PASS = true; % smooth cepstrum for fund. freq. isolation
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CEPSTRUM_LOW_PASS_COEFFS = [1 -0.7];
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FREQ_RESPONSE = true;
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AUTOCORRELATION = false;
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CEPSTRUM_COMPLEX = false; % else real cepstrum
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CEPSTRUM_PLOT = true;
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CEPSTRUM_THRESHOLD = 0.075; % threshold for isolating peaks in cepstrum
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ORIG_LPC_T_COMPARE = false;
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ORIG_SPECTROGRAM = true;
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SYNTH_SPECTROGRAM = true;
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SYNTHESISED_SOUND_LENGTH = 100; % ms
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WRITE = ~true;
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PLAY = ~false;
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% READ SIGNAL
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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[y, Fs] = audioread(strcat('samples/', NAME, '.wav'));
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% take segment of sample for processing
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y = clip_segment(y, Fs, SEGMENT_LENGTH, SEGMENT_OFFSET);
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y_orig = y;
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if PREEMPHASIS
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y = filter(PREEMPHASIS_COEFFS, 1, y);
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end
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L = length(y); % number of samples
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max_lag = Fs/ F0; % for autocorrelation
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% LPC
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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a = lpc(y, LPC_ORDER) % signal, filter order
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est_y = filter(0.02, a, y);
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% COMPARE ORIGINAL SIGNAL WITH LPC (T DOMAIN)
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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if ORIG_LPC_T_COMPARE
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x = 1:AC_DISP_SAMPLES;
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AC_DISP_SAMPLES = min([AC_DISP_SAMPLES L]);
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% plot t domain for original signal and estimation using LPC coeffs
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figure(1)
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plot(x, y(end-AC_DISP_SAMPLES+1:end), x, est_y(end-AC_DISP_SAMPLES+1:end), '--')
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gridh
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xlabel('Sample Number')
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ylabel('Amplitude')
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legend('Original signal','LPC estimate')
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end
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% T DOMAIN PREDICTION ERROR
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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t_domain_err = y - est_y; % residual?
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if AUTOCORRELATION
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figure(2)
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[acs, lags] = autocorr(t_domain_err, max_lag, true, Fs);
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title('Autocorrelation of error in time domain')
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end
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% FREQUENCY RESPONSE
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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if FREQ_RESPONSE
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figure(3)
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%% ORIGINAL FFT
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[freq_dom_freqs, freq_dom_vals] = fft_(y, Fs);
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orig_freq_plot = plot(freq_dom_freqs, 20*log10(abs(freq_dom_vals)), 'black');
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orig_freq_plot.Color(4) = 0.25;
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orig_freq_plot.LineWidth = 1;
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hold on
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%% LPC FILTER RESPONSE
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[filter_vals, filter_freqs] = freqz(1, a, length(freq_dom_freqs), Fs);
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filter_vals_db = 20*log10(abs(filter_vals));
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lpc_freq_plot = plot(filter_freqs, filter_vals_db, 'b');
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lpc_freq_plot.LineWidth = 2;
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% MAXIMA
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% estimate formant frequencies from maxima of LPC filter freq response
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maxima = islocalmax(filter_vals_db);
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maxima_freqs = filter_freqs(maxima)
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maxima_db = filter_vals_db(maxima);
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maxima_plot = plot(maxima_freqs, maxima_db, 'rx');
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maxima_plot.MarkerSize = 12;
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maxima_plot.LineWidth = 2;
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%% PRE_FILTER LPC
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if PREEMPHASIS
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[prefilter_vals, prefilter_freqs] = freqz(1, lpc(y_orig, LPC_ORDER), length(freq_dom_freqs), Fs);
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prefilter_plot = plot(prefilter_freqs, 20*log10(abs(prefilter_vals)), 'g');
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prefilter_plot.Color(4) = 0.8;
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prefilter_plot.LineWidth = 1.5;
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end
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%% PLOT
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hold off
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grid
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xlabel('Frequency (Hz)')
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ylabel('Magnitude (dB)')
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if PREEMPHASIS
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legend('Original Signal', 'LPC Filter', 'LPC Maxima', 'LPC No Pre-emphasis')
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else
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legend('Original Signal', 'LPC Filter', 'LPC Maxima')
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end
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title('Frequency Response For Speech Signal and LPC Filter')
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end
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% CEPSTRUM
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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if CEPSTRUM_COMPLEX
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cep = cceps(y);
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else
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cep = rceps(y);
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end
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cep_filt = filter(1, CEPSTRUM_LOW_PASS_COEFFS, cep);
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if CEPSTRUM_PLOT % plot cepstrum in t domain
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ceps_t = (0:L - 1);
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if CEPSTRUM_LOW_PASS
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c = cep_filt;
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else
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c = cep;
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end
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figure(4)
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hold on
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plot(ceps_t(1:round(L / 2)), c(1:round(L / 2)))
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%% MAXIMA
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% value threshold
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c(c < CEPSTRUM_THRESHOLD) = 0;
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% local maxima
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cep_maxima_indexes = islocalmax(c);
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cep_maxima_times = ceps_t(cep_maxima_indexes);
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c = c(cep_maxima_indexes);
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% quefrency threshold
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cep_time_indexes = 20 < cep_maxima_times;
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cep_maxima_times = cep_maxima_times(cep_time_indexes);
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c = c(cep_time_indexes);
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% 1st half
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cep_half_indexes = cep_maxima_times <= round(L / 2);
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cep_maxima_times = cep_maxima_times(cep_half_indexes);
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c = c(cep_half_indexes);
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maxima_plot = plot(cep_maxima_times, c, 'rx');
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maxima_plot.MarkerSize = 8;
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maxima_plot.LineWidth = 1.5;
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grid
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xlabel('Quefrency (samples)')
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ylabel('ceps(x[n])')
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xlim([0 L / 2])
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title('Speech Signal Cepstrum')
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end
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% CALCULATE FUNDAMENTAL FREQUENCY
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% CEPSTRUM
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if CEPSTRUM_PLOT && length(cep_maxima_times) >= 1
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pitch_period = cep_maxima_times(c == max(c))
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fundamental_freq = 1 / (pitch_period / Fs)
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else
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disp('pitch periods not identified')
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end
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% GENERATE SIGNAL
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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if exist('fundamental_freq')
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excitation = get_impulse_train(fundamental_freq, Fs, SYNTHESISED_SOUND_LENGTH);
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synth_sound = filter(1, a, excitation);
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if WRITE
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audiowrite(strcat('synthed/', NAME, '_o', num2str(LPC_ORDER), '_', num2str(SEGMENT_LENGTH), '_', num2str(SEGMENT_OFFSET), 'ms.wav'), synth_sound, Fs);
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end
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end
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% SPECTROGRAM
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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if ORIG_SPECTROGRAM
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figure(6)
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spectro(y, Fs, WINDOW_NUMBER, WINDOW_OVERLAP);
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colormap bone
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title('Speech Signal Spectrogram')
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end
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if SYNTH_SPECTROGRAM
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figure(7)
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spectro(synth_sound, Fs, SYNTH_WINDOW_NUMBER, SYNTH_WINDOW_OVERLAP);
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colormap bone
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title('Synthesised Vowel Sound Spectrogram')
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end
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% PLAY
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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if PLAY
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sound(y, Fs);
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pause(1);
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if exist('synth_sound')
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sound(synth_sound, Fs);
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end
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end |