Filters

Audio frequencies can be filtered out (attenuated) or conversely permitted by the settings within the filter. In order to apply a filter you must select a range of samples. This can be all samples in the file or only a small piece. Note that filters invoked from the main menu use presets while the buttons on the toolbar permit abnormal parameter adjustment.

When stereo files are loaded, filters can be applied to either track individually or to both tracks simultaneously. For details of how to select one track or both tracks, see Mouse Operations.

Descriptions of the standard filters are listed below.

The Bandpass filter consists of a Low Pass and a High Pass filter combined to allow only frequencies falling within a certain range, usually mid-range. Set the pass frequency with the left slider as a reciprocal of the loaded file's frequency. i.e.: frequency/slider value. Set the steepness of the frequency curve with the right slider in a range of 50 to 100.

When the bandpass filter is invoked from the main menu the frequency is preset at the frequency of the source file divided by 200 with a feedback gain of 100.

When the bandpass filter button on the toolbar is used, the interface is presented allowing you to adjust the bandpass frequency and feedback gain (pitch steepness).

Use the Bandpass filter for recordings such as conversions in noisy rooms to eliminate both high and low frequency sound above and below conversational tones.

Low Pass filter allows all frequencies lower than the cutoff frequency to pass through unaffected.

High Pass filter allows all frequencies higher than the cutoff frequency to pass through unaffected.

Low Shelf filter cuts or boosts the frequencies below the cutoff point. Shelf filters are used to change a broad spectrum of sound rather than attenuating unwanted frequencies.

High Shelf filter cuts or boosts the frequencies above the cutoff point. Shelf filters are used to change a broad spectrum of sound rather than attenuating unwanted frequencies.

Notch filter (Band Reject) is the opposite of the band pass filter which attenuates frequencies around the cutoff point and passes the rest. Sometimes the two are applied in series to cut or boost at the selected frequency.

The Fast Fourier Transition filter in smoothes the transition between amplitude changes at various frequencies.. Setting above zero amplify and filter, settings below zero attenuate and filter.