noise gate implementation

function y=noisegt(x,holdtime,ltrhold,utrhold,release,attack,a,Fs)
%y=noisegt(x,holdtime,ltrhold,utrhold,release,attack,a,Fs);
% holdtime - time in seconds the sound level has to be below the
noise gate with hysteresis
% threshhold value before the gate is activated
% ltrhold - threshold value for activating the gate
% utrhold - threshold value for deactivating the gate > ltrhold
% release - time in seconds before the sound level reaches zero
% attack - time in seconds before the output sound level is the
% same as the input level after deactivating the gate
% a - pole placement of the envelope detecting filter <l
% Fs - sampling frequency
rel=round(release*Fs); %number of samples for fade
att=round(attack*Fs); %number of samples for fade
g=zeros(size(x)) ;
lthcnt=O;
uthcnt=O;
ht=round(holdtime*Fs) ;
h=filter( [(1-a)"2], [l.OOOO -2*a a-21 ,abs(x)) ;%envelope detection
h=h/max (h) ;
for i=l:length(h)
% Value below the lower threshold?
if (h(i)<=ltrhold) 1 ((h(i)<utrhold) & (lthcnt>O))
lthcnt=lthcnt+l;
uthcnt=O;
if lthcnt>ht
% Time below the lower threshold longer than the hold time?
if lthcnt>(rel+ht)
g(i)=O;
else
g(i)=l-(lthcnt-ht)/rel; % fades the signal to zero
end ;
g(i)=O;
g(i)=l;
elseif ((icht) 8! (lthcnt==i))
else
end ;
elseif (h(i)>=utrhold) I ((h(i)>ltrhold) & (uthcnt>O))
1 Value above the upper threshold or is the signal being faded in?
uthcnt=uthcnt+l;
if (g(i-i)<l)
% Has the gate been activated or isn't the signal faded in yet?
g(i)=max(uthcnt/att,g(i-l));
g(i)=i;
end ;
lthcnt=O ;
g(i)=g(i-l) ;
lthcnt=O;
uthcnt=O;
else
else
end ;
end ;
y=x . *g ;
y=y*max(abs(x))/max(abs(y));