title: How do you interpret the frequencies produced by the output of a FFT
body: <p>When you perform an FFT, the frequencies of each of the elements in the output array are represented by:</p>
  
  <p>Frequency at element k is f(k) = k/NT</p>
  
  <p>Where N is the number of samples (hence number of elements in the output array) and T is the time slide in seconds.  f is measured in HZ</p>
  
  <p>My question is, given that formula, the frequency of each element will always be less than 1 HZ and the FFT can never produce higher than 1HZ frequencies</p>
  
  <p>So how do you operate on the higher frequencies?  Like the ones the human ear can hear (20HZ to 20KHZ)</p>
  
  <p>Thanks
  D</p>