fpeak4.m

这是一个用于语音信号处理的工具箱

function [f, amp]=fpeak4(a,radius)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%	jmw
%
%	12/01/93
% 	find freq response peaks of LPC cofa vector
% 	return both peaks and amplitudes of peaks
% 	amp and f are both 1 by 4 vectors
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

echo off

N=256;			% number of points in spectrum
FSOVR2 = 5000;		% fs times 0.5

% compute freq response
[h,w]=jo_freqz(1,a, N,radius);		
mag = abs(h);

% find peaks - start at point n=6 to ignore points below about 125 Hz

inflect_frq = zeros(1,4);	% allocate mem
amp         = zeros(1,4);
cnt = 0;			% inflection counter
slope = sign(mag(8) -mag(7));	% IC's for slope

LIMIT = 192; 	% corresponds to 3750 Hz

for i=9:LIMIT,
	old_slope = slope;		 	% update old slope
	slope     = sign(mag(i) - mag(i-1));	% compute new slope
	if (slope < 0)
		if (old_slope>= 0)
			% inflection found
			cnt = cnt + 1;
			inflect_frq(cnt) = (i)/N*FSOVR2; % remember freq offset
			amp(cnt) = mag(i-1);
			
		end;
	end;
end;

f = [inflect_frq(1) inflect_frq(2) inflect_frq(3) inflect_frq(4) ];
amp = [ amp(1) amp(2) amp(3) amp(4) ];

return;