title: Plotting fft from a wav file using python
body: <p>I am trying to plot the frequency spectrum of a wav file, but it seems like frequency spectrum always matches the time domain signal, with the following code.</p>
  
  <pre><code>import matplotlib.pyplot as plt
  import numpy as np
  
  
  def plot(data):
      plt.plot(data, color='steelblue')
      plt.figure()
      plt.show()
  
  rate, wav_data = wavfile.read("audio_self/on/on.wav")
  plot(wav_data)
  plot(np.abs(np.fft.fft(wav_data)))
  </code></pre>
  
  <p>Am I doing something wrong?</p>