Removing silence

The Remove Silence command detects sections of audio that fall below a given loudness threshold, and replaces those sections with absolute silence. Remove Silence gives you the option of actually deleting the silent sections from the selected audio clips, splitting long audio clips into a greater number of shorter audio clips.

Sonar treats passages of absolute silence intelligently. It doesn’t store stretches of silence on disk, and thereby conserves disk space. During a passage of absolute silence, Sonar sends no signal to the digital output port; this results in cleaner audio playback. Remove Silence is great for cleaning up your final audio mix, because it can mute all audio tracks in which the live performers were “laying out.”

Using Remove Silence to split long audio clips into smaller ones opens a variety of creative possibilities.

The parameters in the Remove Silence dialog box are used to specify exactly what you mean by silence. More precisely, Remove Silence employs what is called a digital noise gate. The gate is a type of filter, it passes data through, or stops it from passing through, according to certain criteria. Parameters in the dialog box specify the conditions under which the gate is opened and under which it closes again.

The digital noise gate parameters are described in the following table.

Parameter	Meaning
Open Level (dB)	The loudness threshold for opening the noise gate. The gate officially opens when loudness rises above this level, although it can open earlier because of the Attack Time.
Close Level (dB)	The loudness threshold for closing the noise gate. The gate officially closes when loudness falls below this level, although it can stay open later because of the Release Time.
Attack Time (ms)	The value in this field is the interval of time after the volume reaches the Open Level for the gate to fully open. Opening the gate gradually produces a fade-in effect instead of an instant on-off sound.
Hold Time (ms)	The minimum time for the gate to stay open. Hold Time is useful when you’ve set high open and close levels, for example, when your source signal is very loud. Noise gates set this way tend to react to repeated percussive passages (such as drum rolls) by repeatedly opening and closing; this can sound unpleasant. By setting a hold time, you can ensure that the gate stays open long enough during percussive passages.
Release Time (ms)	The amount of time after the Close Level is reached that the gate actually closes. This lets the tail end of sounds pass through without being clipped.
Look Ahead (ms)	The value in this field causes the gate to open slightly before the sound reaches the Open Level so you don’t lose the sound’s attack.

To remove silence

1.	Select the audio data to be affected.

2.	Choose Process > Apply Effect > Remove Silence to open the Remove Silence dialog box.

Figure 387. The Remove Silence dialog box.

3.	Set the digital noise gate parameters as described in the table above.

4.	Select the Split Clips check box to delete the silent sections of audio.

5.	Click OK to remove silence from the selected data.

Sonar processes the audio as directed.