Filter out calm parts of audio, let through really loud ones
Found it! From the [Adobe Premiere effects help][1]:


  Dynamics effect The Dynamics effect provides a set of controls that
  can be combined or used independently to adjust audio. Use either the
  graphical controls in the Custom Setup view, or adjust values in the
  Individual Parameters view. This effect is available for 5.1, stereo,
  or mono clips.
  
  AutoGate
  
  Cuts off a signal when the level falls below the specified threshold.
  Use this control to remove unwanted background signals in recordings,
  such as a background signal in a voice-over. Set the gate to close
  whenever the speaker stops, thus removing all other sounds. The LED
  display colors indicate the gate’s mode: open (green), attack or
  release (yellow), and closed (red). Use the following controls for
  Gate: Threshold
  
  Specifies the level (between –60 and 0 dB) that the incoming signal
  must exceed to open the gate. If the signal level falls below this
  level, the gate closes, muting the incoming signal. Attack
  
  Specifies the time the gate takes to open after the signal level
  exceeds the threshold. Release
  
  Sets the time (between 50 and 500 milliseconds) the gate takes to
  close after the signal level has fallen below the threshold. Hold
  
  Specifies the time (between 0.1 and 1000 milliseconds) the gate stays
  open after the level has fallen below the threshold.
  
  [1]:
  https://helpx.adobe.com/premiere-pro/using/audio-effects-transitions.html