Lowpass filters block high pitched, frequencies (treble) but allow low pitched frequencies (bass) to pass. They can be used to reduce high end hiss noise or remove unwanted sounds above the given cutoff frequency. If you were to apply a lowpass filter with a cutoff frequency of 1000Hz on speech, it would make it sound muffled and deep. Lowpass filters can also be used to eliminate aliasing noise when used before downsampling.
Highpass filters block low pitch frequencies, but allow high pitched frequencies to pass. They can remove deep rumbling hum or remove unwanted sounds below the given cutoff frequency. If you were to apply a highpass filter with a cutoff frequency of 1000Hz on speech, it would make it sound thin and hollow.
| Low/Highpass Settings | ||
|---|---|---|
| Group | Setting | Description |
| Cutoff frequency | Initial cutoff (Hz) | Sets the constant cutoff frequency for static filtering or the initial frequency for dynamic filtering. |
| Final cutoff (Hz) | Sets the cutoff frequency at the end of the selection, allowing you to fade from one cutoff to another over the selection. Dynamics must be checked to set this value. | |
| Settings |
Lowpass, Highpass |
Sets the type of filter to use. Select Lowpass to keep only the frequencies below the cutoff frequency. Select Highpass to keep only the frequencies above the cutoff frequency. |
|
Static, Dynamic |
Sets whether the filter is constant or changing. Select Static to keep the cutoff frequency constant throughout the selection during processing. Select Dynamic to fade the cutoff frequency from the initial value to the final value over the duration of the selection. | |
| Steepness | Sets how sharply the filter cuts off frequencies outside the cutoff frequency. A higher steepness makes the filter sharper, but it also increases processing time. In technical terms, the steepness specifies the number of second order cascade filters used. | |
See Also: Bandpass/Stop, Equalizer, Noise Reduction, Spectrum Filter, Presets