Varying delay on audio signal is too rapid

Hello!

I'm trying to add a chorus effect to an audio signal. The difference equation for creating a chorus effect is: y(n) = a*x(n) + b*x(n-t(n)) So, the delay of the added signal is varying. The variance is described by this equation: t(n) = t0 + A*sin(2*pi*f*k), where f is a normalized frequency. k is an integer and likewise the function's variable.

I've created an algorithm that doesn't generate errors, but doesn't generate a chorus effect either. The problem is that t(n) is varying too quickly. A period takes just five samples. The usual value for f is 0.25. I have also used f=0.1 so the effect should have been notable. There are relations between fs, f and t0 but I cant see how to use them in a way that makes any difference - c*fs=f, 0<c<1, d*fs=t0, d element of R

function Y = chorus(X,fs)

f = 0.25;

t0 = 0.05; % 50 ms delay

tau = [zeros(size(X))];

a = 0.2; b = 0.8; % abs(a) and abs(b) should sum up to 1

A = t0*fs*0.99; % amplitude of delay variation should be below the initial delay

N = length(X)

for k = 1:N

      tau(k) = round(t0*fs + A*sin(2*pi*f*k)); % values in tau have to be integers.
  end

tau = [zeros(1,tau(1)) X']; % to keep index above zero

Y = [];

for k = 1:length(X)

      Y = [Y a*X(k)+b*X(round(k-tau(k)))];

end

[Aravinth Ananth]

Hello fedric can i get your code please i need it please