Noise Gate

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Use the Noise Gate to reduce the level of sound below a specified threshold level.

A noise gate is a kind of "dynamics processor" that allows audio above a specified threshold level to pass through unaffected (gate "open"), and stops or reduces sounds below the threshold level (gate "closed").

Noise Gates may be used to cut the level of residual noise between sections of a recording. While this is essentially a very simple effect, this Noise Gate has a number of features and settings that allow it to be both effective and unobtrusive and well suited to most types of audio.

Accessed by: Effect > Noise Gate...
Noise Gate.png


Select Function

Select whether you want to apply the noise gate, or analyze the noise level:

  • Gate: Apply the noise gate.
  • Analyze Noise Level: Analyze the level of the selected audio. All other controls are ignored when this option is selected.

When analyzing the noise level, ensure that the start of the selection lies within a region of noise only. The measurement is taken from the first half second of the selection. The analysis displays the measured level, and suggests a setting for the Gate Threshold setting.


Stereo Linking

When Link Stereo Track is selected (the default), the gate will work on the channels of a stereo track as a pair and change the level of both channels by the same amount when the level in both channels fall below the threshold. This option is generally recommended, but will leave low level noise un-gated if there is sound above the threshold in the other channel.

When Don't Link Stereo is selected, the gate will adjust the amplitude separately for the left and right channels of a stereo track. This may be preferred when left and right channels have unrelated sounds, such as perhaps two sides of a conversation. For conventional stereo tracks it may cause a peculiar sensation of sound moving across the stereo field.


Apply Low-Cut filter

Removes sub-sonic frequencies including DC off-set (off by default). The filter is a gentle (6dB/octave) roll-off sub-bass filter. Options are provided for the corner frequency at either 10 Hz or 20 Hz. The gate will generally be more accurate with this option set to "No" (no low-cut filter), but may be useful if the source material has noticeable DC-offset, or very low frequency rumble.

DC corrected tracking is used whether or not the Low-Cut Filter has been selected, so the gate is largely immune to DC-offset problems.


Gate frequencies above

This slider control has a range up to 10 kHz (default = 0).

  • When set to zero, the gate acts on all of the audio.
  • When set above zero, the gate acts on audio frequencies above the set kHz level, and lower frequencies pass through the gate unaffected.

This option may be useful in cases where there is substantial high frequency hiss, but relatively little noise at lower frequencies.


Level reduction

This slider control determines the amount of attenuation (negative amplification) that is applied when the gate is "closed" (below the threshold level). At -100 dB, the gate stops the sound completely when closed, unless the "Gate frequencies above" is set higher than zero. If "Gate frequencies above" is higher than zero, the frequencies above the specified kHz level are stopped completely when the amplitude level is below the threshold.

Lower (more negative) setting attenuate the signal more, resulting in less noise passing through the closed gate, but may also produce noticeable pumping of the audio as the gate opens and closes. See the section on Suggested Workflow below.


Gate threshold

When the audio level drops below this threshold the gate will 'close' and the output level will be reduced. When the audio level rises above this threshold the gate will 'open' and the output will return to the same level as the input.


Attack/Decay

This setting controls how quickly the gate opens and closes.

  • At the minimum (10 ms) the gate will fully open and close almost instantly as the audio level crosses the threshold. This could cause the gate to 'flutter' or 'snap'.
  • At the maximum (1000 ms), the gate will begin to slowly open (fade-in) 1 second before the sound level exceeds the Threshold, and will gradually close (fade-out) after the sound level drops below the Threshold over a period of 1 second.


Suggested Workflow

  1. Analyse the noise level
  2. Test the gate on a short selection with the Level Reduction set to -100 dB
  3. Adjust the Gate Threshold if necessary and retest.
  4. Adjust the Level Reduction slider and test. For the most 'transparent' results avoid setting the Level Reduction any lower than absolutely necessary.
  5. When the settings are correct, apply to the entire song.


Buttons

Clicking on the command buttons give the following results:

  • Manage gives a dropdown menu enabling you to manage presets for the tool and to see some detail about the tool. For details see Manage presets
  • Preview plays a short preview of what the audio would sound like if the effect is applied with the current settings, without making actual changes to the audio. The length of preview is determined by your setting in Edit > Preferences > Playback, the default setting is 6 seconds.
  • OK applies the effect to the selected audio with the current effect settings and closes the dialog
  • Cancel aborts the effect and leaves the audio unchanged, closing the dialog
  • Help Button brings you to the appropriate page in the Manual, this page


Links

|< Index of Effects, Generators and Analyzers

|< Effect Menu