title: How can I extract the 'x' axis of from a numpy array?
body: <p>I try to plot the graph with this code:</p>
  
  <pre><code>db = librosa.core.amplitude_to_db(y)
  
  plt.title('Noise level')
  plt.xlabel('Time')
  plt.ylabel('Volume, db')
  plt.plot(db)
  </code></pre>
  
  <p>As a result I got such graph:</p>
  
  <p><img src="https://i.stack.imgur.com/E4m6M.png" alt="https://i.stack.imgur.com/E4m6M.png">.</p>
  
  <p>Otherwise, I should plot the graph in <em>time</em> for <code>x</code> axis and <em>db</em> in <code>y</code> axis. What should I do to achieve that?</p>