title: Speech Recognition UnknownValueError
body: <p>I have tried it on python shell 3.5.8</p>
  
  <pre><code>import speech_recognition as sr
  import webbrowser as wb
  
  chrome_path = 'C:/Program Files (x86)/Google/Chrome/Application/chrome.exe 
  %s'
  
  
  # obtain audio from the microphone  
  r = sr.Recognizer()  
  with sr.Microphone() as source:  
     print("Please wait. Calibrating microphone...")  
     # listen for 5 seconds and create the ambient noise energy level  
     r.adjust_for_ambient_noise(source, duration=5)  
     print("Say something!")  
     audio = r.listen(source)  
  
  # recognize speech 
  try:
      text = r.recognize_google(audio)
      print("I thinks you said '" + r.recognize_google(audio) + "'")
  
      f_text='https://www.google.co.in/search?q=' + text
      wb.get(chrome_path).open(f_text)
  #except sr.UnknownValueError:  
  #  print("I could not understand audio")  
  except sr.RequestError as e:  
     print("error; {0}".format(e))
  
  except Exception as e:
     print (e)
  </code></pre>
  
  <pre class="lang-none prettyprint-override"><code>File "C:\Users\manoj\AppData\Local\Programs\Python\Python35\lib\site- 
  packages\speech_recognition\__init__.py", line 858, in recognize_google
  if not isinstance(actual_result, dict) or 
  len(actual_result.get("alternative", [])) == 0: raise UnknownValueError()
  speech_recognition.UnknownValueError
  </code></pre>