anchor: Source:getFilter
  Gets the filter settings currently applied to the Source.
  settings = Source:getFilter()
  settings table The filter settings to use for this Source, or nil if the Source has no active filter. The table has the following fields:
  settings.type FilterType The type of filter to use.
  settings.volume number The overall volume of the audio.
  settings.highgain number Volume of high-frequency audio. Only applies to low-pass and band-pass filters.
  settings.lowgain number Volume of low-frequency audio. Only applies to high-pass and band-pass filters.