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Audacity's Noise Reduction Effect

Hi there and welcome to this video where we're going to be looking at the noise reduction effect. So previously, we looked at the noise gate effect which allows us to reduce the background noise when the level is lower than what we set with a threshold. The noise reduction effect however allows us to remove the noise throughout the audio, including where they're speaking. So if you want to use this effect on your own audio, I recommend recording just the room sound to effectively use this plug in. If you haven't recorded any room sound at the start of your audio, then you could always find sections in your audio where there's no speaking and try and use that instead for the noise reduction effect to remove this background sound. It really needs to be a constant sound like a computer fan, for example. So the noise in this recording is a fan. So constant noise, not spikes of audio, for example, here we could remove the constant noise at the start, but we couldn't remove this spike of aud...

io. OK. So now let's actually solo the third track and now I'm just going to click on this drop down box above and then go on to name and let's rename this to keep organized and let's call this noise reduction. OK? Let's have a listen back to this clip. So you can hit the start there. We have the background sound. So I'm just going to click and drag over this background sound. This is important for the noise reduction effect and I'll show you this now. So let's go up to effect and then go down to noise reduction. OK. So we actually have two steps we need to do in this noise reduction plug in the first step here says select a few seconds of just noise. So audacity knows what to filter out, then click, get noise profile. So that's what I did. I slept in a few seconds there. It doesn't have to be as long as this, but I do recommend a few seconds. Let's now hit, get noise profile. You'll notice the plug in is closed. It's meant to do that. So now we need to go back up to effect and then down to noise reduction again. And now we're on step two. So now you can preview the audio. So that plays back for five seconds. You can still hear the fan sound, but it's not as loud. I'm just going to move the mouse over to the left and right of this highlighted area. So these finger icons appear and just move it over here. So we get around a second of silence and then we can hear the audio. So when we apply this effect, it's only going to be applied to this area. However, after I've showed you the settings of this noise reduction effect, I'll show you how to apply it to the whole track. Let's make it a bit longer at the end as well. And now let's go back to effect and then down to noise reduction and preview this again. OK? So this is me talking into the microphone, let me just move this out the way so we can see what's going on. OK. So this is me talking into the microphone. OK? Now let's look at the second step. The first setting here is noise reduction. So this allows us to select how much we want to reduce the noise in decibels. So higher values will reduce the noise more and lower values will reduce it less. However, if you reduce it too much, then it may ruin the quality of your audio. So I don't recommend setting this too high, but just for this example, let's increase it all the way to Max, which is 48 decibels and now preview this back. OK. So this is me talking into the microphone, you may have heard there that the voice recording wasn't quite as clear, but a lot of the background noise was removed. But for this, I'm going to drop it down to 12 again. And now let's talk about sensitivity going down, we have this sensitivity slider. So the higher the value here, the more noise that will be removed. So just remember the settings that you apply here is applied to all of the audio. So where the voice speaks and where the voice isn't speaking. So if this sensitivity slider, I recommend choosing between one and five as if you have this set too high, then you may ruin the quality of your audio. But just for this example, again, let's use an extreme one. Let's go up to 24. OK. So this is me talking into the microphone you may have heard there, it did ruin the voice slightly. So let's drop this down a bit. I'm going to choose four and let's preview this back now. OK? So this is me talking into the microphone. We may have some issues or artifacts when applying noise reduction. So if you do experience this and I recommend adjusting the sensitivity and you may also wish to adjust the number of smoothing bands. So adjusting these bands is also going to adjust the sound. So be careful as it may damage the quality of your audio here. So make sure you use your ear for this one as well. So if you do have any issues when applying noise reduction, you may wish to increase the number of bands. So the default is free, but you can try higher values if you need. So after pressing preview and you can hear some artifacts or issues in your audio. Then you may wish to increase the frequency smooth bands as this will spread the noise reduction into neighboring bands. So this may smooth out the artifacts and make them sound more acceptable. However, again, if you set this too high, then it may make the audio sound less clear. But just for this example, let's try an extreme setting again. OK. So this is me talking into the microphone, OK? It didn't sound too bad with this high setting, but I'm going to go back to the default, which is free. OK? So this is me talking into the microphone. OK? Let me now talk about reduce and residue. So if you have reduce enabled and this will filter out or reduce the noise from the audio that we have selected. So when you press preview, you can hear the audio with the noise removed. However, if you have residue enabled, then this allows you to hear only the audio that you wish to remove. So just the noise that you wish to remove. So if we have residue enabled and we listen back with a preview button and we can hear some of the voice in the audio, then we know that the noise removal is removing the voice as well as the noise. If that's the case, then I recommend going back to the above settings to adjust these. So you can't hear the voice as much in the playback. So let's have a listen back with this on residue mode. OK. So we can hear a bit of the voice there, but it doesn't sound like too much of a problem. However, if I increase sensitivity to max and then preview this back, you think you can hear there more of the voice in the audio. So I recommend decreasing this as a voice may sound a bit unclear, right? Yeah. So I recommend going between residue and reduce and finding that sweet spot where you're moving the noise, but you're not damaging the voice too much. OK? So this is me talking into the microphone so there we can still hear the background noise. But again, if the background noise is quite loud and you try to remove too much, it may damage the quality of the voice. So if I do reduce say 20 decibels then increase the sensitivity slightly. You'll notice there will be less of the background noise, the audio won't be quite as clear. OK? So this is me talking into the microphone and of course, we can smooth this out a bit more if we wish. OK. So this is me talking into the microphone, it doesn't sound too bad. But if I do select residue here, you'll notice we'll be able to hear quite a lot of the voice. He um so for this example, I'm just going to drop this to 12 and let's put the sensitivity on six and let's put the bands on four so of residue, you could still hear the voice but it wasn't too loud. So let's change the mode back to reduction and let's hear this back. OK. So this is me talking into the microphone. It's not perfect, but it's more acceptable. And now let's hit. OK. And you'll notice that it has removed the background noise as we can see that wave has disappeared. Now, let's play this back. OK? So this is me talking into the microphone. So as I just highlighted this area here, it's only going to remove the noise from here. But if you want to remove the noise from all of your audio, what you can do is undo this by pressing command Z on Mac or control Z on windows and then double click on this audio track to select all and then go back to effect and then go down to noise reduction and you can see that it saved our settings and it's also saved the noise profile from before. So now we can hit. OK? And it will apply this noise reduction to the entire audio track. OK? So now let's play this back and hear what this sounds like. OK. So this is me talking into the microphone. This room is quite noisy, you may be able to hear that there is a fan sound. So of course, we can still hear the background noise. But if we compare it to the original recording you'll be able to hear. It's a lot quieter. OK. So this is me talking into the microphone. This room is quite noisy, you may be able to hear. So this is with the noise reduction. OK. So this is me talking into the micro, this is with the noise gate. OK. So this is me talking into the microphone and this is the unprocessed audio. OK? So this is me talking into the microphone. So I recommend learning how to use the noise gate and the noise reduction effect and then apply them to your clips if you need to. So you can also try using both the noise gate and the noise remover plug in at the same time. But to be honest, if you want your audio to sound as good as possible, you want to try and record it with as little noise as possible. So if you do have any background noise that you wish to remove, I recommend using the techniques I taught you and applying them to your own audio. If you wish though, you can use the same audio file as me as this is attached to a lecture in a previous video in the section. So a noise gate may be more preferred as it doesn't actually damage the audio. It just turns down the audio at the quiet parts to help remove the background noise. However, the noise removal effect can remove the unwanted noise whilst it's speaking. And also whilst there's no speaking, so it really depends on which is best for you. But like I said, ideally want to record without any background noise, but that's not always possible. OK. So that is the essentials of noise reduction in audacity. In the next few videos, we're going to continue looking at processing the audio with EQ and compression. So I hope you found this video useful and I'll see you in the next one.