Noise Gate with a sidechain?

Hi all

I’m looking for a Noise Gate that has a side-chain facility so a different track/audio source can open and close a gate a track.

For those who aren’t sure what I mean, see this video

In other words, nothing passes on the track with the gate over it unless the threashold is reached on a different track plugged into the sidechain

Thanks in anticipation.


Topic moved to “Adding Features”.

Thank you for your suggestion. We already have a feature request logged:

“Built-in Noise Gate
Should include real-time preview and optional side chain filter, where the trigger for the Gate would be another track or a filtered version of the current track or another track”

so I’ve added your ‘vote’ for this feature.

The nit-picker is raising his hand.
This isn’t a side chain noise gate. This is a side chain gate.
A gating effect is cause to happen from work on a second sound channel. It does not trigger a gate that then starts evaluating and processing noise.


You’re right. The nit-picker wins :smiley:

An envelope-follower may suffice …

LOL! The hardware gates I’ve used (with sidechain facility) are still gates with the second (gate controlling) signal plugged directly into the detector circut. Some have SEND/RECEIVE jacks for the detector circut with a bridge to join them together (sometimes a simple piece of wire) when the sidechain isn’t in use…

… but they’re still sold as “Noise Gates”… because of the other “gate” controls are still needed, not just the side-chain.

I was wondering how to setup the detector audio track to control the track to be processed, but I’ve started to use the Auto-Duck (for a different job) and putting the detector track UNDER the track to be processed works just fine… as long as you can select (as in highlight the few seconds or whatever) what part of the track to be process should be affected… just like the Auto-Duck. I mention this in case that part of the Auto-Duck code can be re-used for the side-chain idea.

Just my 2c.


Funnily enough, that is one aspect of Auto Duck that I really don’t like. It is not really ‘intuitive’. I can remember that the track(s) to be modified must be selected (just like all other effects), but I forget whether the control track needs to be above or below the selected track(s). Wouldn’t it be better if the effect had a drop-down list (multiple choice control) with a list of available tracks so that you can select any available track in the project as the control track?

You could start a new Adding Features topic about that. It might get some votes.


I’ve put Steve’s envelope-follower code into a plugin (attached) …
Envelope-Follower plugin in action.gif
You could use a gate after the envelope-follower, (but that’s optional).
ENV-FOL.ny (2.01 KB)


Will give this a solid attempt over the weekend. Thanks. I’m still a n00B to Audacity and didn’t have a clue what to do with Steve’s E-F code.


Set properly, when a gate closes it is muting unwanted audio or noise. That’s why it’s called a noise gate. This has nothing to do with the sidechain. How it is triggered, whether it be a separate audio source, or more commonly the source signal bandwidth limited, it is still gating off unwanted sounds, which in my book is considered noise.

i.e.: When I gate a rack tom on a drum kit, I’ll bandwidth limit the trigger with a narrow response, depending on the tuning of the tom, somewhere around 315hz . This way cymbals, kick drum, and to an extent, the snare, all of which are unwanted signals in a tom mic, will not open said gate, and since the area of 315Hz is usually a pretty dominant tom frequency the gate will open without having to squash the threshold which in turn would shave off the peak response of the drum. NOTE: The gate must be inserted pre-eq/pre-fader so that eq and level changes (not gain) do not affect the performance of the gate.

Need reference, read:

-Glenn (FlipFlops2001)
Independent Audio Engineer (FOH, MON, SE, Studio): 1979-present

A gate may be used to reduce the level of sound that you want to keep, in which case it’s not a “noise” gate, it’s just a “gate”. That was koz’s pedantic point.
First line of Wikipedia article:

A > noise gate > or > gate > …

Note also that that is totally irrelevant to Audacity as effects are applied directly to the track audio data, so eq / fader settings are irrelevant.

Nevermind! Got it! :slight_smile: