title: How to apply Butterworth filter to my code?
body: <p>I want to filter out noises from a voicerecording and normalize it. Currently I am struggeling with a Butterworth bandpass filter.</p>
  
  <p>How do I apply this in my code? (I'm new to Python)</p>
  
  <pre><code>from numpy import nditer
  from pydub.audio_segment import AudioSegment
  from scikits.audiolab import wavread
  
  from scipy import signal
  
  # Stereo to mono
  stereo_sound = AudioSegment.from_wav('voice.wav')
  mono_sound = stereo_sound.set_channels(1)
  mono_sound.export('voice_mono.wav', format='wav')
  
  podcast = wavread('voice.wav')
  
  for frame in podcast:
      print(frame)
  
  print("\n")
  print("\n")
  
  
  # Read mono file
  podcast = wavread('voice_mono.wav')
  frames = podcast[0]
  max_iter = 2000
  i = 0
  for frame in nditer(frames):
      i += 1
      if i &lt; max_iter:
          print(frame)
  
  
  # Apply Butterworth filter
  
  # Do Butterworth filter and save as new wav
  b, a = signal.butter(4, 100, 'bandpass', analog=True)
  </code></pre>
  
  <p>Thanks alot!</p>