Nature of Noise source. soundsc (noise, 10000);

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Robyn Morrison
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1 Noise Sources Voiceless aspiration can be produced with a noise source at the glottis. (also for voiceless sonorants, including vowels) Noise source that is filtered through VT cascade, so some resonance information will be maintained in output. Breathy voice can be approximated by combining (adding) a noise source and the voiced source Not true breathy voice, which has a different vibrational cycle than modal voice. Different glottal filter would be required.

2 Nature of Noise source Gaussian noise noise = randn(1,4000) soundsc (noise, 10000); hist (noise,20) spectrum (noise,10000)

3 Combined Source Model Noise Voiced + noise * AH_interp * AH_gain pulse * AV_interp * AV_gain =

4 syn3 function signal = syn3 (srate,frame_dur,nf,ftable) % synthesize.m % Louis Goldstein % November 2009 % formant synthesizer % usage: % [out, t] = syn3 (srate,frame_dur,ftable) % % input arguments: % srate sampling rate (in Hz) % f0 fundamental frequency (in Hz) % frame_dur duration of each frame in milliseconds % Ftable character string containing filename of F table % Row 1: AV % Row 2: f0 % Row 3: AH % Row 4 to Row 4+nf-1: formant frequencies % Row 4+nf to Row 4+2*nf-1: formant bandwiths % %returned arguments: % signal vector with synthesized waveform samples % location of parameters in table iav = 1; if0 = 2; iah =3; if1 = 4; ib1 = if1+nf;

5 % location of parameters in table iav = 1; if0 = 2; iah =3; if1 = 4; ib1 = if1+nf; AV_gain = 100; AH_gain =.05; % voiced gain factor % voiceless gain factor FBW = get_fbw(ftable); nframes = size(fbw,2); dur = nframes * (frame_dur / 1000 );% duration in seconds samps_per_frame = floor(srate * (frame_dur / 1000));

6 % generate sources % voiced source f0 = FBW(iF0,:); AV = FBW(iAV,:)*AV_gain; voiced = make_impulse_av(f0, srate, frame_dur, AV); nframes = min ([floor(length(voiced)./ samps_per_frame) nframes]); RG = 0; % RG is the frequency of the Glottal Resonator BWG = 100; % BWG is the bandwidth of the Glottal Resonator [b_glo,a_glo]=resonance(srate,rg,bwg); % filter impulse train thru low-pass filter % to get approximation to shape of glottal pulse voiced=filter(b_glo, a_glo, voiced); % noise source AH = FBW(iAH,1:nframes)*AH_gain; noise = randn(1, length(voiced)); % Gaussian noise % take derivative (calculate velocity source from pressure source) noise = filter ([.5.5], 1, noise); AH_int = interp(ah, samps_per_frame); % compute composite source in = voiced + (noise.* AH_int);

7 function pulses = make_impulse(f0, srate, frame_dur,av); % Input parameters % f0 vector of f0 values % srate sampling rate (Hz) % frame_dur duration of each f0 frame (corresponds to slide in get_f0) % AV vector of voicing amplitudes frame_length = floor(frame_dur * srate / 1000); % frame length in samples length_f0 = length(f0); % interpolate f0 so it has a value for every sample and scale in cycles/ sample cont_freq = interp(f0/srate, frame_length); cont_av = interp(av,frame_length); % calculate elapsed cycles for every sample elapsed_cycles = cumsum(cont_freq); %calculate percentage way through current cycle cycle_percent = rem(elapsed_cycles,1); shift = [0 cycle_percent(1:end-1)]; % set pulses (1s) and 0s elsewhere pulses = cycle_percent<shift; % will be true only when cycle boundary is crossed pulses = cont_av.* double(pulses);

8 New FBW file: aba3.txt Arbitrary Char Arbitrary nos. Must be longest line F AV F Pairs: frame val AH F F F F F B B B B B Make sure each line specifies value for frame 1, and for last frame

9 Stages in modeling VCV (1) Set vowel formants and bandwidths: use constant values for entire sequence (2) Find location of silence (or low amplitude closure voicing) and set low value of AV there. (3) Find values of F1-F3 at closure onset and release. Interpolate between vowel F values and these values over the frames where you see transition (4) For aspirated stops, add AH and remove AV during release transitions. Also increase B1 during this interval.

10 aba

11 aba3.txt F AV F AH F F F F F B B B B B

12 apa.txt F AV F AH F F F F F B B B B B

Location of sound source and transfer functions

Location of sound source and transfer functions Sounds produced with source at the larynx either voiced or voiceless (aspiration) sound is filtered by entire vocal tract Transfer function is well modeled