4.1.5. Frequency Filters

Frequency Filters are only available in VoceVista Video and VoceVista Video Pro.

Frequency Filters are a powerful tool that allows you to listen to the different frequency ranges of a sound separately. This enables you, for example, to inspect individual overtones of a recording, or to reduce or amplify the singer’s formant and hear the effect of this change.

Using a Frequency Filter

Figure 4.9. Using a Frequency Filter


Figure 4.9 shows a frequency filter that removes any frequencies outside of the range from 300 to 500 Hz. The left side of the image shows the spectrogram with a time selection. Only the selected time range is filtered.

The right side of the image shows the spectrum. The only part of the spectrum that is left by the filter is the second harmonic at 400 Hz. All other parts are removed, and will not be audible when the recording is played back. However, you can still see the outline of the removed parts.

Using Frequency Filters

Create a new filter by clicking on FiltersAdd new frequency filter. If the new filter is not visible, scroll the Frequency Scale down or zoom it out until you see the filter.

You can move and resize the filter with the mouse. Here is an overview of the various controls:

Filter Controls

Figure 4.10. Filter Controls


Move filter

Simply grab the frame of the filter with the left mouse button to move it to a different frequency range.

Move multiple filters in parallel

If multiple filters exist, a new handle will appear next to the handle for resizing the frequency range. This new handle allows to move all existing filters in parallel as a group.

Resize filter

The width of the filter can be changed by moving the red resize handles in the middle of the filter. If you hold Ctrl while using the resize handles, the filter is resized symmetrically around its center.

Toggle additive or subtractive mode

The + and buttons change the behavior of the filter. An additive filter (+ Mode) keeps the filtered frequencies and removes everything else. A subtractive filter (- Mode) removes the filtered frequencies and keeps everything else.

Additive filter (+ Mode)

Figure 4.11. Additive filter (+ Mode)


Subtractive filter (- Mode)

Figure 4.12. Subtractive filter (- Mode)


Change filter strength

By default, the filters are an all-or-nothing affair. This can be changed by moving the Filter Strength Slider (shown in Figure 4.10).

Deactivate filter

This button allows you to turn off a filter, so that it is still there, but has no effect. If you want to reactivate the filter, simply click the button again. This allows you to experiment with the effect of the filter.

Delete filter

When you are done with a filter, click this button to completely remove it.

Filters menu

The Filters menu has entries to add a new filter, and to toggle between the + and modes. It also has the following entries:

Enable real time filter preview

If this option is checked, the effect of the filter is shown immediately, both on the spectrogram, and for playback. This means you can see and hear how your recording is affected by the filter. You can generally leave this on, but in some cases it may be helpful to turn it off. In particular, you might want to arrange filters and still see the unmodified spectrogram before turning the filters on.

Apply filters permanently

This command will apply the active filters to the current selection of your recording. In contrast to the real time preview, which does not change your sound file, this is a permanent alteration of the recording (although it can be undone by clicking on EditUndo).