Truncate Silence

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FrenchFlagSmall.png Truncado de silencio


Truncate Silence automatically reduces the length of passages where the volume is at or below a specified level.
  • Silences are detected that remain at or below the specified level for at least the specified length of time.
  • The detected silences are then made shorter by automatically deleting a section from the middle of the silent region.
  • For the purposes of this effect, the words "silence" and "silent" mean sounds that are below the detection level.
  • "Detected silences" mean sounds that are below the detection level for at least the specified length of time.
Accessed by: Effect > Truncate Silence...
TruncateSilence.png

Operation Mode

There are two methods available for shortening the silence. The simplest method is by truncating the silence (default mode) and a more advanced method is by compressing the length of the silence.

Truncate Detected Silence

When this method is selected, silences are simply shortened to the specified duration (see example below).

When this option is selected, the "Truncate to:" (seconds) control is available lower down the interface and the "Compress to:" (percent) control is grayed out. All detected silences are shortened to the same duration.

Compress Excess Silence

This is a more advanced mode that allows silences to be shortened proportionally according to their original duration.

When this method is selected, silence in excess of the specified duration is reduced to a percentage of its original duration (see example below).

When this option is selected, the "Compress to:" (percent) control is available lower down the interface and the "Truncate to:" (seconds) control is grayed out. Because silences are reduced by a specified percentage the final duration of each detected silence varies according to its original length.

Detecting Silences

There are two controls that determine which audio will be treated as "silence":

  1. Level (dB): to be treated as silence, the audio must be at, or below this level.
  2. Duration (seconds): to be treated as silence, the audio must remain below the specified level for at least this amount of time; this value must be at least 0.001 seconds.

Reducing the length of detected silences

There are two controls that determine how much silence is removed, and hence the final length of each silence. Only one of these controls is available at a time, depending on whether the simple Truncate Detected Silence or the advanced Compress Excess Silence mode has been selected.

  • Truncate to (seconds): when the audio remains below the specified level for at least the specified duration, it will be reduced to this duration.
  • Compress to (percent): when the audio remains below the specified level for at least the specified duration, the excess silence is reduced. That is, if the original silence is 10 seconds longer than the specified minimum, then there is 10 seconds of excess silence. The percentage refers to this 'excess' silence, and not the entire detected silence.

Examples

Truncate Detected Silence examples:

Shorten all silences that are longer than 2 seconds to 2 seconds

This may be useful for shortening inter-track gaps from an LP or cassette recording.

  1. Set the Operation mode in the drop-down to "Truncate Detected Silence"
  2. Set the detection "Level:" control. If there is noticeable background noise you may need to set this as a higher (less negative) value than the default.
  3. Set the detection "Duration:" control to 2 seconds. Silences of 2 seconds or more will be chosen by the effect for truncation.
  4. Set the "Truncate to:" control to 2 seconds. All detected silences will be truncated to 2 seconds.
  5. Click OK

Shorten silences that are longer than 20 seconds to 5 seconds

This may be useful for removing long pauses in a speech recording, without affecting the natural rhythm of the speech.

  1. Set the Operation mode in the drop-down to "Truncate Detected Silence"
  2. Set the detection "Level:" control.
  3. Set the detection "Duration:" control to 20 seconds. Silences of 20 seconds or more will be chosen by the effect for truncation.
  4. Set the "Truncate to:" control to 5 seconds. Silences of 20 seconds or more will be truncated to 5 seconds. Silences of less than 20 seconds will remain unchanged.
  5. Click OK.


Compress Excess Silence examples:

Compress silences that are longer than 2 second

This may be useful when a subtle reduction of longer silences is required while maintaining a sense of the relative length of each silence, In this example we will use a compression setting of 50% for simplicity.

  1. Set the Operation mode in the drop-down to "Compress Excess Silence"
  2. Set the detection "Level:" control.
  3. Set the detection "Duration:" control to 2 seconds.
  4. Set the "Compress to:" control to 50 percent.
  5. Click OK
  • Silences that were originally 2 seconds or less will be unaffected.
  • All silences that were longer than 2 seconds are shortened.
  • The new length of the silence will be comprised of 2 seconds (the ignored duration) plus half (50%) of any additional silence.

Example: With the above settings, for an 8 second silence, there are 6 seconds beyond the 2 second detection period. The 8 second silence will therefore be reduced to: 2 seconds plus 50% of 6 seconds = 2 + 3 = 5 seconds.

Compress all silences to half their original duration

Strictly speaking all silences cannot be selected because there is a fixed minimum length of silence that can be detected of 0.001 seconds. However,0.001 seconds (1 millisecond) is an extremely short period, so we are able to compress all noticeable silences to half their original length. This may be useful to speed up a recorded lecture or dictated notes without affecting the words.

  1. Set the Operation mode in the drop-down to "Compress Excess Silence"
  2. Set the detection "Level:" control.
  3. Set the detection "Duration:" control to 0.001 seconds. Note that if set to 0 the OK and Preview are greyed out and a message is shown above the buttons: Minimum detection duration: 0.001 seconds.
  4. Set the "Compress to:" control to 50 percent.
  5. Click OK


Limitations

Truncate Silence only removes audio, it does not reduce or eliminate noise in the silent sections that it keeps.

Warning icon Avoid using Truncate Silence on selections which have fade outs or fade ins, since it may remove the quietest part of fades. If you need to add fades, apply Truncate Silence before adding fades.


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