You can remove silent passages from audio regions in the Remove Silence window. The basic process is simple: all amplitude values below a threshold level are removed, and new regions are created from the remaining passages.
The parameters of the Remove Silence window are:
Threshold: Use to define the amplitude level that a passage must exceed, in order to be defined as a region. In terms of the number and length of regions created by the process, this is the most important parameter. As a general rule: a higher Threshold value leads to numerous short regions. Low values create fewer large regions.
Minimum Time to accept as Silence: Use to define the length of time that a section must be below the Threshold value, before it is considered a gap. Very small values tend to increase the number of regions, because even short dips in amplitude are interpreted as silence. Higher values prevent sections of audio from being interrupted by fluctuating amplitudes.
Pre Attack-Time: Use to add a defined amount of pre-roll to the beginning of all regions created by the Remove Silence process. High threshold values prevent any amplitudes with slower attack times from being chopped. This function is useful for nonpercussive material such as vocals, wind instruments, strings, and so on. Overlaps are permitted—the pre-delayed start point of a region can extend back to the end of the previous region—but only if the Threshold value is not exceeded. The Pre Attack Time doesn’t affect the anchor position, which means the absolute position of the audio data (in the project) is retained.
Post Release-Time: Use to define an automatic release time for the end points of all regions, avoiding abrupt cutoffs to amplitudes that fade out gradually (particularly if you have set a high Threshold value); for example, cymbals, open hi-hats, snares with long reverb tails, vocals, and so on. This parameter does not allow overlaps, which means that region end points cannot extend beyond the start point of the following region. The Post Release Time doesn’t affect the anchor position, which means the absolute position of the audio data (in the project) is retained.
Search Zero Crossings: Select this checkbox to automatically snap the region start and end points to the nearest waveform zero crossings.
In the Project Audio Browser, Control-click an audio region, then choose Remove Silence from the shortcut menu.
Set parameters in the Remove Silence window.
Note: Depending on the material in the audio file, all parameters can affect the number and division of regions. Try different values to see what produces the best result. The graphic display of the region updates to show the result of your changes.
Click OK.
If you selected a region that is used in the Tracks area, a dialog asks if you want to replace the region in the Tracks area with the new regions.
Do one of the following:
To replace the region in the Tracks area with regions created by the Remove Silence function: Click Replace or press Return. This ensures that the relative timing of the individual audio segments remains unaltered.
To have the regions appear only in the Project Audio Browser: Click No. You can add regions manually from the Project Audio Browser.
To learn about different uses for Remove Silence, see Uses for Remove Silence.