[x, Fs] = audioread('wannabe_in_la.wav');
ft_x = fft(x);

Fc = 300; 
p = Fs/(2*Fc);

H_f = zeros(length(ft_x), 1);
do = length(H_f)/(2*pi);
for k = 1:length(H_f)
  if k < do*(pi/p)
    H_f(k) = 1;
  end
  if k > do*(2*pi - pi/p)
    H_f(k) = 1;
  end
end

tic;
ft_x = fft(x);

ft_y = ft_x .* H_f;

y = ifft(ft_y, 'symmetric');
toc;