code: def calc_db(peak, refval, mphonecaldb=0):
      u
      if refval == 0:
          return np.nan
      if hasattr(peak, '__iter__'):
          peak[peak == 0] = np.nan
      pbdB = mphonecaldb + (20. * np.log10(peak / refval))
      return pbdB
docs: u""" 
      Converts voltage difference into decibels : 20*log10(peak/refval)
      
      :param peak: amplitude
      :type peak: float or np.array
      :param refval: This can be either a another sound peak(or RMS val), to get the dB difference, or the microphone mphone_sensitivity
      :type refval: float
      :param mphonecaldb: If using the microphone sensitivity for refval, provide the dB SPL the microphone was calibrated at. Otherwise, leave as 0
      :type mphonecaldb: int
      :returns: float -- decibels difference (comparision), or dB SPL (using microphone sensitivity)