f=200:200:3400;

for i=1:18


h=sin(pi*f./8000)./(pi*f./8000);
g=20.*log10(h);
end
plot(f,g)
d=0.2
10^(-d/10)


z=[0 100 300 500 599 1000 1800 100000];
F=(z+600)./(z-600);
F1=abs(F);
ad=6+20.*log10(F1)