eq_circuit.m

这是一个用于语音信号处理的工具箱

%This function calculates the equivalent circuit parameters R,L and C
%
%The algorithm used is fairly straightforward, and can be found in the paper
%by Flanagan and Ishizaka. The only modification made is that the Radiation Impedances
%are included in the same vectors...that is the last value in the R,L and C vectors would 
%represent radiation parameters
%
%A vocal tract area function file can be loaded and this can be used 
%to calculate the equivalent circuit parameters.  However, since this
%is a program to be used for educational purposes, the area of the vocal tract
%is assumed to be constant (The value of this can be changed from the
%control window). The interested user can load an area function file and observe
%the glottal areas for specific vowels.

function [R,L,C] =  eq_circuit(No_of_Segments,A);


Len = 1;

air_density =  1.14e-03;
viscosity = 1.864e-04;
sound_velocity = 3.53e04;
 
%Values for frequency etc. were obtained from Ching-Jang Wu's thesis and program
frequency_r=0.1531;
frequencyr_radiation=57.99;
frequencyl_radiation=0.000546;


for i=1:No_of_Segments 
   R(i) = frequency_r*Len/(A(i)^(3/2));
   L(i)=(air_density/2)*(Len/A(i));
   C(i)= Len/(air_density*sound_velocity^2)*A(i);
end

%Now find values for radiation impedances
R(No_of_Segments+1)= frequencyr_radiation/A(No_of_Segments);
L(No_of_Segments+1) =frequencyl_radiation/sqrt(A(No_of_Segments));
C(No_of_Segments+1) = 0;