title: Can´t use librosa with python 3
body: <p>I have installed librosa correctly with pip3 on ubuntu subsystem on windows, but when I try to execute a simple program like this one:</p>
  <pre><code>import librosa
  data, sr = librosa.load('sound.mp3')
  print(data.shape)
  </code></pre>
  <p>It is what happens:</p>
  <pre><code>/home/henistein/librosa/librosa/core/audio.py:144: UserWarning: PySoundFile failed. Trying audioread instead.
    warnings.warn('PySoundFile failed. Trying audioread instead.')
  Traceback (most recent call last):
    File &quot;/home/henistein/librosa/librosa/core/audio.py&quot;, line 128, in load
      with sf.SoundFile(path) as sf_desc:
    File &quot;/home/henistein/.local/lib/python3.8/site-packages/soundfile.py&quot;, line 740, in __init__
      self._file = self._open(file, mode_int, closefd)
    File &quot;/home/henistein/.local/lib/python3.8/site-packages/soundfile.py&quot;, line 1264, in _open  
      _error_check(_snd.sf_error(file_ptr),
    File &quot;/home/henistein/.local/lib/python3.8/site-packages/soundfile.py&quot;, line 1455, in _error_check
      raise RuntimeError(prefix + _ffi.string(err_str).decode('utf-8', 'replace'))
  RuntimeError: Error opening 'sound.mp3': File contains data in an unknown format.
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File &quot;PerfectPitch.py&quot;, line 2, in &lt;module&gt;
      data, sr = librosa.load('sound.mp3')
    File &quot;/home/henistein/librosa/librosa/core/audio.py&quot;, line 145, in load
      y, sr_native = __audioread_load(path, offset, duration, dtype)
    File &quot;/home/henistein/librosa/librosa/core/audio.py&quot;, line 169, in __audioread_load
      with audioread.audio_open(path) as input_file:
    File &quot;/home/henistein/.local/lib/python3.8/site-packages/audioread/__init__.py&quot;, line 116, in audio_open
      raise NoBackendError()
  audioread.exceptions.NoBackendError
  </code></pre>
  <p>What am I doing wrong?</p>