Clean up audio tracks and sound clips

After you've adjusted levels, your first task in the noise reduction and sound removal process is to remove background noises. And there are two ways to do that in Audition: Hiss Reduction and Noise Reduction.

Noise Reduction is the best methodology. I'll show you both in this lesson. I'm working here inside the spectral frequency view. It's much easier to see noise here. I've got this file that has several noise examples.

We're gonna work with a couple of them. It's the same music clip repeated over and over with different kinds of noises applied to it. I've got a hum here, like that. You can see the hum down there. This has some hiss. And this one has a fan noise in it. So you can see the fan noise in the bottom there, the hiss on the top. This one has the kind of sound that you get with old vinyl records. Here are some clicks and pops. And we've got a cough here, and a cell phone ring here.

We'll work on the background noises here, which are hiss and static. Let's just take a look at the two effects that we're gonna work with here.

Go to Effects, go to Noise Reduction/Restoration. And there's Noise Reduction and Hiss Reduction, both of them are process effects, meaning that they work only here inside the Editor view, inside the Editor panel. They do not work in a multi-track session. They're also destructive, meaning that if you make a change and then save it with the original name in the original file folder, you will change that original file. So you need to be careful when you work with effects here inside the Editor panel.

All right, we're gonna work with the Hiss Reduction effect first, click on that, opens up this dialog box. It uses what's called a Noise Floor. And the Noise Floor is already applied here from a previous session.

I'm gonna go back to the Default view, which is just a flat line. What it means is that any sound below this line will be removed and any sound above this line will remain. So let's go get a Noise Floor. To do that, we need to sample the audio we're gonna work with.

I'm gonna pull this off to one side like this. I'm gonna zoom in this one because this is the hiss. I want to zoom in on that and get a sample of the hiss. So I am going to zoom in on by right clicking here on the time ruler, dragging up that little part there so you can see the whole thing. There is the hiss right there at beginning before the music kicks in.

So to get a Noise Floor, you want to try to get the sound, the bad sound that you want to remove but don't get the regular sound, the foreground sound, the music. So I'm gonna go grab this hiss by just taking my Time Selection Tool and selecting it like so. And since hiss is a broadband sound, meaning it covers all frequencies, I want to use the Time Selection Tool so I grab frequencies from the top to the bottom here.

Right now I've got this selection, I need to now capture it. So inside the Hiss Reduction effect, you notice this button is now active. If I click on that, and that captures the noise floor. And this is that view of that sound basically from the low, and here the low frequency to the high frequency and the relative decibel levels. So anything below this will be cut out, anything above this will be retained. That's how the Hiss Reduction works.

So now I'm gonna select the entire clip here. So I'm gonna pull this thing down a little ways, take my Eye Beam tool here and select that whole thing there .Now we're gonna work with that.

I can preview this Default setting here. The Default setting is flat but now that I have adjusted this, we've got these settings here, 8dB and 24dB. I'll explain that in a second. So I'm gonna preview this by pressing this play button there. You can still obviously hear that hiss, it's not dramatically different. And you can hear that the music has changed.

What I'm gonna do is I'm gonna play this and adjust some of these settings. This setting here, the Noise Floor says how much you're going to remove, the higher it goes the more you're removing, the more that's below the line here that you're gonna cut out. And then Reduce By says how may decibels you're gonna cut it out by, how many decibels will you reduce the noise.

Let's just experiment with that by clicking on this, run it through a couple of times. I think you can hear that, the sound gets kind of muffled. The greater we reduce things by raising the Noise Floor or raising the decibels that we've reduced.

I'm gonna let you listen to just the hiss so you got a chance to see what actually being removed. I'm gonna click on this button there, that check box and we'll try it again. So you can see the farther right I go, the more of the music I pick up. That's telling you what you're removing and you're removing some music when you go farther to the right.

So the Hiss Reduction effect in my view is not as good as the Noise Reduction effect, which we're gonna work with here in just a moment, but you might as well try it out and you might find in certain circumstances that it does work better than Noise Reduction. Right, I'm gonna close this down now.

Now I'm gonna change to different view. I want to change to the Preview Editor because when your work with Noise Reduction, I think it's good idea to see how things are going to change. So I'm gonna switch over here to the Preview Editor by clicking this button in the upper right-hand corner.

Now we've got the before and the after when we work on Noise Reduction. Let's take a look at that effect. You go down Noise Reduction/Restoration, you see you've got a Capture Noise Print option. Down here you did not have a Capture Noise Floor option. That was built into the effect, but here it's separate and built into the effect. So I'll open up the effect there.

You can see that it has this little button much like the other one. But here the button is active whether you've got a selection or not. I'm gonna select this hiss by just hovering over and making up selection, like that. Now I'm gonna capture that noise print and that's what it looks like.

The new options here are how much you want to reduce it by in terms of how much of that little noise you want to take out and how much in terms of decibels do you want to remove. It's kind of similar to the noise floor but here it's a little more specific, I think.

I'm gonna select the entire file here by just taking my little Eye Beam tool there and my Time Selection Tool and selecting that entire file, there we go. Now we see it work all the way across, see things have been removed there. Now they haven't actually been removed, this is the preview mode here.

So let's lift this back up here, we'll do a little bit of previewing by just playing it out for a while and see what that sounds like. You hardly hear the hiss at all, you hear little artefact, little kind of verbals, kind of metallic sounds at the beginning and the end. You probably hear that little sound there.

I'm gonna start playing with these controls here, I'm gonna reduce the amount of hiss that's removed and reduce the decibels and then increase them again. So I think in the music it sounds pretty good, the changes are not that obvious. But when we get the silent passages here, you can hear that kind of verbally, underwater metallic sound. Nevertheless, I think Noise Reduction effect works very well

Let's try in on something else. I'm gonna close this down. We'll go shift to some other location here and I'll move this down the line here to the static, just right there. Let's just play that for a second. Notice the static, this is the final record where there's static and clicks. And the Noise Reduction tool will not get rid of clicks. It gets rid of the constant background noise, not the discreet sounds like clicks.

So what I want to do here is remove the static first and then remove clicks later with another effect or another set of effects. So we're looking here at this particular one, at the end, I've got a fairly good segment there where there aren't any obvious big clicks. So I'm gonna select that part with the Eye Beam tool like that with Time Selection tool and I go back to Noise Reduction effects, Noise Reduction.

I am going to get the Noise Print here because I've got a new Noise Print. When you'll watch, you'll see this is different when we do capture that. It's different now. It's got that static look instead. You see that it has already tried to remove that part right there. Now I'm gonna select the entire section of that file there. Time Selection tool, drag all the way across like that, you watch what happens down here. Right away, it tries to fix it down there.

And now we'll give this a little test to see how it sounds. So you're hearing that, oh, my gosh, we didn't get rid of much, but in fact, we got rid of quite a bit. I'll show you the before and the after here. I'm gonna zoom in just end here and click away for a moment. We'll just select just this little area at the end here, like that, and we'll see what the before and the after is here. Try this again. Pull this up a little bit. We'll just loop through that. I'll turn it on and off down here. Here it's on, here it's off. On. Off.

So you can see that it does remove something. Now one way that you can approach Noise Reduction is to do a little bit at a time, come back and apply it a couple of times. So I'm gonna show you how that works. I'll close this down for time being, let me just get the whole thing again, like this, bring that back in again, Effects, Noise Reduction.

You don't need to capture the noise print again because the last noise print is still stored in it. I'm gonna knock the settings down a bit here. Let me bring them down this to 80 percent, like this, and apply it. And I'm going to apply it again. I'm gonna get a new noise sample log. We have changed it. Let me get this sample right there. And we'll try this again, Noise Reduction, get the new noise print, which will be a little different, you can see that. Let's select the entire file again, like so. And then we'll do it again, keep it at the low level, maybe just up just a little bit, try that again, apply it. 

Each time we do it, it gets a little bit better.

Let's just listen to it now, just see what it sounds like. Let's listen to the end. It's just a little bit better, but there's still some static. And obviously, the more times we do this, the more we'll remove. But it's good to do little applications to try to remove sound a little bit at a time. It's a more effective way to do it when you've got stuff that's kind of difficult to remove. We'll settle on this after a while where we think we've got a good amount removed.

Let me deal with these little pops and scratches there. Let's take a look at one more thing, back up here that fan noise. Let's listen to this. There's hum and then there's the fan noise. The part of the noise that applies to the Noise Reduction is not so much the hum but it's the fan up here. So I'm gonna select an area that's not the entire frequency range. So I'm gonna go over here and get my Marquee Selection Tool and select this area here which is above the hum, basically right about there. I want to remove just that and I'll remove the hum with the Sound Remover Tool later.

So I'm gonna go get that, go to Effects. I'll get Noise Reduction/Restoration, Noise Reduction, capture this noise print, which will be different. I'm gonna get rid of that across the board. Let's just see what that sounds like. I'll just bring this up, like this, bring it up like that. We'll select the entire segment here, the Time Selection Tool. There, all selected.

We'll then try that out and see how that sounds. Let's look at the hum, but we'll try to remove some of that high frequency stuff there. I can hear that low frequency hum but we're getting rid of the static on top and you can see how it's working here, you can see how that's disappearing down here.

So that'll be, kind of, the strategy here when you got this hum, plus, this background sound that runs through all the frequencies. Save the hum to Sound Remover but get rid of the rest of the background stuff using the Noise Reduction effect. So again the Noise Reduction effect fits into the workflow by being the first Noise Reduction tool that you use. You use it to remove unwanted background sound.