gusucode.com > 《MATLAB图像与视频处理实用案例详解》代码 > 《MATLAB图像与视频处理实用案例详解》代码/第 19 章 基于语音识别的信号灯图像模拟控制技术/voicebox/frq2bark.m
function [b,c] = frq2bark(f,m)
%FRQ2BARK Convert Hertz to BARK frequency scale BARK=(FRQ)
% bark = frq2bark(frq) converts a vector of frequencies (in Hz)
% to the corresponding values on the BARK scale.
% Inputs: f matrix of frequencies in Hz
% m mode options
% 'h' use high frequency correction from [1]
% 'l' use low frequency correction from [1]
% 'H' do not apply any high frequency correction
% 'L' do not apply any low frequency correction
% 'z' use the expressions from Zwicker et al. (1980) for b and c
% 's' use the expression from Schroeder et al. (1979)
% 'u' unipolar version: do not force b to be an odd function
% This has no effect on the default function which is odd anyway
% 'g' plot a graph
%
% Outputs: b bark values
% c Critical bandwidth: d(freq)/d(bark)
% The Bark scale is named in honour of Barkhausen, the creator
% of the unit of loudness level [2]. Criitical band k extends
% from bark2frq(k-1) to bark2frq(k).
%
% There are many published formulae approximating the Bark scale.
% The default is the one from [1] but with a correction at high and
% low frequencies to give a better fit to [2] with a continuous derivative
% and ensure that 0 Hz = 0 Bark.
% The h and l mode options apply the corrections from [1] which are
% not as good and do not give a continuous derivative. The H and L
% mode options suppress the correction entirely to give a simple formula.
% The 's' option uses the less accurate formulae from [3] which have been
% widely used in the lterature.
% The 'z' option uses the formulae from [4] in which the c output
% is not exactly the reciprocal of the derivative of the bark function.
%
% [1] H. Traunmuller, Analytical Expressions for the
% Tonotopic Sensory Scale? J. Acoust. Soc. Am. 88,
% 1990, pp. 97-100.
% [2] E. Zwicker, Subdivision of the audible frequency range into
% critical bands, J Accoust Soc Am 33, 1961, p248.
% [3] M. R. Schroeder, B. S. Atal, and J. L. Hall. Optimizing digital
% speech coders by exploiting masking properties of the human ear.
% J. Acoust Soc Amer, 66 (6): 1647?652, 1979. doi: 10.1121/1.383662.
% [4] E. Zwicker and E. Terhardt. Analytical expressions for
% critical-band rate and critical bandwidth as a function of frequency.
% J. Acoust Soc Amer, 68 (5): 1523?525, Nov. 1980.
% The following code reproduces the graphs 3(c) and 3(d) from [1].
% b0=(0:0.5:24)';
% f0=[[2 5 10 15 20 25 30 35 40 45 51 57 63 70 77 ...
% 84 92 100 108 117 127 137 148 160 172 185 200 ...
% 215 232 250 270 290 315]*10 [34 37 40 44 48 53 ...
% 58 64 70 77 85 95 105 120 135 155]*100]';
% b1=frq2bark(f0); b2=frq2bark(f0,'lh');
% b3=frq2bark(f0,'LH'); b4=frq2bark(f0,'z');
% plot(b0,[b0 b1 b2 b3 b4]-repmat(b0,1,5));
% xlabel('Frequency (Bark)'); ylabel('Error (Bark)');
% legend('Exact','voicebox','Traunmuller1990', ...
% 'Traunmuller1983','Zwicker1980','Location','South');
% Copyright (C) Mike Brookes 2006-2010
% Version: $Id: frq2bark.m,v 1.8 2010/01/06 10:12:04 dmb Exp $
%
% VOICEBOX is a MATLAB toolbox for speech processing.
% 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
% http://www.gnu.org/copyleft/gpl.html or by writing to
% Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
persistent A B C D P Q R S T U
if isempty(P)
A=26.81;
B=1960;
C=-0.53;
D=A*B;
P=(0.53/(3.53)^2);
Q=0.25;
R=20.4;
xy=2;
S=0.5*Q/xy;
T=R+0.5*xy;
U=T-xy;
end
if nargin<2
m=' ';
end
if any(m=='u')
g=f;
else
g=abs(f);
end
if any(m=='z')
b=13*atan(0.00076*g)+3.5*atan((f/7500).^2);
c=25+75*(1+1.4e-6*f.^2).^0.69;
elseif any(m=='s')
b=7*log(g/650+sqrt(1+(g/650).^2));
c=cosh(b/7)*650/7;
else
b=A*g./(B+g)+C;
d=D*(B+g).^(-2);
if any(m=='l')
m1=(b<2);
d(m1)=d(m1)*0.85;
b(m1)=0.3+0.85*b(m1);
elseif ~any(m=='L')
m1=(b<3);
b(m1)=b(m1)+P*(3-b(m1)).^2;
d(m1)=d(m1).*(1-2*P*(3-b(m1)));
end
if any(m=='h')
m1=(b>20.1);
d(m1)=d(m1)*1.22;
b(m1)=1.22*b(m1)-4.422;
elseif ~any(m=='H')
m2=(b>T);
m1=(b>U) & ~m2;
b(m1)=b(m1)+S*(b(m1)-U).^2;
b(m2)=(1+Q)*b(m2)-Q*R;
d(m2)=d(m2).*(1+Q);
d(m1)=d(m1).*(1+2*S*(b(m1)-U));
end
c=d.^(-1);
end
if ~any(m=='u')
b=b.*sign(f); % force to be odd
end
if ~nargout || any(m=='g')
subplot(212)
semilogy(f,c,'-r');
ha=gca;
ylabel(['Critical BW (' yticksi 'Hz)']);
xlabel(['Frequency (' xticksi 'Hz)']);
subplot(211)
plot(f,b,'x-b');
hb=gca;
ylabel('Bark');
xlabel(['Frequency (' xticksi 'Hz)']);
linkaxes([ha hb],'x');
end