Error using conv (line 27) A and B must be vectors.

input_signal = wavread(‘C:\Users\Shibalik\Desktop\sample.wav');      %noisy signal

filter_size=40;                       
iterations=8000;
step_size=.02;

i am getting an error while convulving the input and the impulse. please help me out.

% Create the impulse response for the desired signal
impulse=zeros(filter_size,1);
for (i=1:5)
    impulse(((i-1)*filter_size/5)+1)=1/i;    
end

% Convolve the impulse with the input signal to generate the desired signal
desired_signal = conv(input_signal, impulse);

[Usopp]

Use conv2() instead of conv()