Certain techniques in audio production have stood the test of time, becoming staples in the arsenal of professionals seeking pristine sound quality. One such technique is Strip Silence This semi-automatic approach has been an integral part of Pro Tools for ages, offering an efficient means of creating audio clips based on the amplitude of their content. Using Strip Silence, audio engineers can effortlessly eliminate unwanted background noise during the ingestion process, similarly to the capabilities of a noise gate. However, what sets Strip Silence apart is its unparalleled degree of control, allowing producers to achieve outstanding results with utmost precision.

Three Buttons In Strip Silence

Many users are only familiar with Strip Silence in its most common application, offering a more controllable alternative to a noise gate for dealing with noise and spill. However although the name of the function is Strip Silence, it can be used for more than that. Strip is only one of three buttons. What about the other two?

We have a Strip button to keep only the material over the threshold, similar to a noise gate. We have Separate which keeps creates clips based on the threshold and other settings in the same way as Strip would but keeps material both above and below the threshold. And there is a third button the Extract button, which only keeps material below the threshold

Using Extract To Isolate Room Tone

it is this Extract Button which we’ll look at in more detail in this article in which Steve DeMott shares his technique for creating clean room tone. Over to Steve:

In audio post projects, I often find that the production recordist either didn’t get enough room tone, or forgot to get it all together. Luckily, this is not a problem thanks to the Extract feature in Strip Silence.

The process for getting contiguous room tone from a dialogue track is straightforward, but does require you have access to the raw production audio & not just the video editors edited audio tracks. For most of us, this is just part of the deliverables and we access the production audio through Field Recorder Workflow, but you can get around this without needing the Field Recorder Workflow features that are only in Pro Tools Ultimate.

When I have a scene where I need to fill the background with room tone I start by making a copy of a dialogue track on my “work” track (which is also my Field Recorder Guide Track). You want to make sure you are using a boom track & not one of the lavalier tracks. I’ll listen through the options to find the right source using the Field Recorder search results. If you don’t have Ultimate, you could just copy in the appropriate boom track from the raw production audio folder.

The first step is to open up the clip to the full extent of the recording. This is why you need the production audio & not just the video editor’s files, which will likely only have 2 second handles on the head & tail.

With the full clip selected I will open Strip Silence (⌘+U) and move the Threshold slider down until most of the silence is selected. I find it’s typically around -40 on the slider & then hit the Extract button.

I’m now left with (mostly) the “silence” from the clip, which is really the room tone that I’m after.

Now I go through & listen to each clip. Some clips will just have too much movement to be useful (footfalls, rustling, etc.). I will delete those as I come across them. The rest I will go through to adjust the clip bounds to remove any clicks or pops at the start/end of the clip. I will also cut out any moments of unusable noise in the middle, further adjusting those clips bounds.

As I finish a clip I will then right click & select “Snap to previous” so it abuts the previous clip & then I listen across the edit point to make sure there are no clicks or pops, adjusting as needed to make a smooth transition. I may also adjust clip gain to keep things homogenous.

I keep at this until I’ve gone through all the available clips, then give it one final listen to check my work. Once I’m happy with what I have I select all the clips and consolidate them (⇧⌥3) to make a single clip that I can drag down to the background track for contiguous tone fill for the scene.

You might be tempted to crossfade these clips before consolidating them, but that can cause problems, since the crossfade will use parts of the clip beyond your edit (by the amount of the crossfade) & that could reintroduce those clicks & pops that you so tediously removed that are just beyond the clip bounds. It’s best to use a good set of headphones & just get each clip transition to be smooth by adjusting the clip bounds.