Filtering frequency-domain data¶

Frequency-domain data (a FrequencySeries or a Spectrogram) can be filtered using an arbitrary filter using the filter() methods of those objects:

`FrequencySeries.filter`(filt, *kwargs)	Apply a filter to this `FrequencySeries`.

`Spectrogram.filter`(filt, *kwargs)	Apply the given filter to this `Spectrogram`.