www.pudn.com > voicebox2.zip > GLOTLF.M

function u=glotlf(d,t,p) 
%GLOTLF   Liljencrants-Fant glottal model U=(D,T,P) 
% d is derivative of flow waveform: must be 0, 1 or 2 
% t is in fractions of a cycle 
% p has one row per output point 
%	p(:,1)=open phase [0.6] 
%	p(:,2)=+ve/-ve slope ratio [0.1] 
%	p(:,3)=closure time constant/closed phase [0.2] 
% Note: this signal has not been low-pass filtered 
% and will therefore be aliased 
% 
% Usage example:	ncyc=5; 
%			period=80; 
%			t=0:1/period:ncyc; 
%			ug=glotlf(0,t); 
%			plot(t,ug) 
 
 
%      Copyright (C) Mike Brookes 1998 
% 
%      Last modified Thu Apr 30 17:22:00 1998 
% 
%   VOICEBOX home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 
% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
%   This program is free software; you can redistribute it and/or modify 
%   it under the terms of the GNU General Public License as published by 
%   the Free Software Foundation; either version 2 of the License, or 
%   (at your option) any later version. 
% 
%   This program is distributed in the hope that it will be useful, 
%   but WITHOUT ANY WARRANTY; without even the implied warranty of 
%   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
%   GNU General Public License for more details. 
% 
%   You can obtain a copy of the GNU General Public License from 
%   ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to 
%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
if nargin < 2 
  tt=(0:99)'/100; 
else 
  tt=t-floor(t); 
end 
u=zeros(size(tt)); 
de=[0.6 0.1 0.2]'; 
if nargin < 3 
  p=de; 
elseif length(p)<2 
  p=[p(:); de(length(p)+1:2)]; 
end 
 
te=p(1); 
mtc=te-1; 
e0=1; 
wa=pi/(te*(1-p(3))); 
a=-log(-p(2)*sin(wa*te))/te; 
inta=e0*((wa/tan(wa*te)-a)/p(2)+wa)/(a^2+wa^2); 
 
% if inta<0 we should reduce p(2) 
% if inta>0.5*p(2)*(1-te) we should increase p(2) 
 
rb0=p(2)*inta; 
rb=rb0; 
 
% Use Newton to determine closure time constant 
% so that flow starts and ends at zero. 
 
for i=1:4 
  kk=1-exp(mtc/rb); 
  err=rb+mtc*(1/kk-1)-rb0; 
  derr=1-(1-kk)*(mtc/rb/kk)^2; 
  rb=rb-err/derr; 
end 
e1=1/(p(2)*(1-exp(mtc/rb))); 
 
 
ta=tt