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Whether one is producing music, podcasts, game sounds, or film sound effects, Digital Audio Principles provides the tips and techniques that will make the project a success. Author Dave Schroeder explains the basics of digital audio production techniques and covers the essential hardware and software. He also discusses sound theory, frequency response, the range of human hearing, and dynamic range.
In this section, we're going to talk about two more sound tools that can be really helpful, in terms of dealing with noise and artifacts in your sounds. We'll look a little bit at noise reducers, and I'll show you a little example of that, and then we'll talk about dither. So noise reduction soundware, or sound tools, can help you eliminate things like pops and clicks that you might have on old vinyl records if you record them in, or different little static noises. You can use them to reduce things like background hum or other sounds. I'm going to actually go ahead and use one on a voiceover track that I recorded.
We did a little interview in a kitchen, and needless to say, a kitchen is not the quietest place in the world to do an interview. There's quite a bit of noise and just kind of general machinery running around. I'm going to show you how we can apply a plug-in and actually reduce some of the noise a little bit. So let me get us a nice view of this, so that we can kind of listen to more of the voice and less of the noise. Let's just take a listen. (inaudible speech) So you hear that kind of that airy sound that there's a lot of noise there.
There may have even been, believe it or not, something like a refrigerator or air conditioner running in there. Lots of noise. So anyway, I want to try and get rid of that. I want to keep that voice. I want to keep hearing it. But I want to get rid of some of that noise as much as possible. So I'm going to go into the AudioSuite, then open up, from the Noise Reduction world, the X-Noise Mono plug-in, which is a waves plug-in. Again this is in Pro Tools, but you'll actually find stand-alone noise reduction software that if you have a sound file and you just want to bring it in and try and reduce the noise, you can do it as a stand-alone thing. Or you can find lots of plug-ins that will work with your digital audio software.
So the first thing I'm going to do is teach my noise-reduction software to go ahead and learn what this noise sounds like, to kind of memorize what the noise is. So I'm going to highlight something that's just noise, and I'm going to go ahead --and here, we call it learning that. Let that run through a few times. Okay. So now we've got what it thinks is the noise.
So now I'm going to go ahead and highlight a little bit more of this section and preview it through our plug-in. And then I'm going to bring up the threshold for this. (inaudible speech) So can you hear the difference there? We've reduced the amount of noise pretty well. It's not completely gone, but we can hear more of the voice. We'll A/B it and compare it.
I'll play it, and then I'll bypass it, so we can hear how much noise was originally there. (inaudible speech) So that's a lot more palatable now. Of course, we can go farther, and I will; I'll show you. One thing I should mention that with a lot of noise-reduction software is ultimately the way it works is it's actually taking away some of the frequencies. It's turning down specific frequencies and certain volumes, and at some point when you start to do that, you also start to take away some of the frequencies, or sound information, or material that's the material you want to hear.
In this case, the interviewee's voice. (inaudible speech) So you can see that we can actually do quite a bit to reduce the difference between noises. Let's A/B it one more time, and see what a difference we have made. (inaudible speech) So you can hear that the quality of the voice does change a little bit and fine- tuning your noise-reduction software, it takes a lot of time and a lot of love.
You've got to get pretty close to it and spend some time with it, because there's always just the perfect balance between getting rid of as much noise as you can and starting to affect the sonic quality of what you want to hear, or her voice. So it takes a little bit of playing, but in certain circumstances it works like a charm. It kind of all depends on what the noise is like. If it's a constant and kind of consistent flowing noise like that, it's a lot easier to zero in on it, kind of learn it and give it a profile, and then reduce it a little bit. If it's kind of erratic and coming and going, you won't have as much luck reducing the noise.
But I think a little bit less noise is still better than all that noise. So it's something to look into it. Now let's take a look at dither, or dithering. Now this could be one of the least interesting plug-ins to look at, and I should explain what dither is. When we work in a session like this, I'm in a session with a bit resolution of 24 bits or 24 bit depth, when I want to change that bit resolution to any lower resolution, like 20-bit or 16-bit, we effectively have to re-sample the sounds. And the reason you want to go to a different bit depth is that if I want to put this on an audio CD or even use it as a source file to generate an MP3 from, I need to dither it down to 16 bits.
So we're working at 24 bits, and I want to go to a 16 to put this on a disc. In other situations, you might find yourself working at 32 bits and needing to downsample down to 16 bits. Well, what happens is we have to re- sample that sound, and with digital re-sampling and downsampling, a lot of times you run into trouble with some of the quieter passages in your sound file. The sampling can have a tendency--it doesn't always happen--but it can have a tendency to introduce a little bit of distortion there, because basically it's not seeing enough. It can't quite find enough information to sample, and so it gets a little confused.
It wants to find something, but it doesn't quite find it. So what dithering is, it's the act of actually adding in very, very quiet noise, so that there's some program material there. There's some data that the sampler can look at and pay attention to, and it reduces the possibility of there being little artifacts, or little moments of slight distortion. Now in a lot of scenarios, dithering is not absolutely necessary, and you might not even notice that you didn't dither. The effect might not be noticeable. But sometimes it will happen, and you'll hear little artifacts in your new 16-bit sample, and you'll wonder where they came from.
Well, dither is what you want to apply to the file before you export it. So let's assume we have a master nix. It's pretty simple. You open up the tool and you decide what bit rate you're headed for. So were headed to 16 bits, see? Here I have the options of 20 bit and 16 bit. That's because I'm at 24 bit. I have to be going down in some direction, so we're going to go down to 16 bit. And all you do is select your sound file. If it's your final mix that you bounced everything to, select it, hit Process.
It won't look that different. It won't sound that different to you, but something good is taking place. So we'll go ahead and just apply it, so we can see it. Really not even that big of a difference when you go to play it back here in this situation, slightly, but nothing to go crazy about. But the point is, if you have it and have access to it, it's wise to do it in order to avoid the possibility of getting some distortion and some artifacts.
We'll talk a little bit more about this in the chapter on mastering. So that does it for sound tools and for plug-ins in general. Hopefully, I've shown you enough of what's possible and kind of what different plug-in families do and the different kinds of effects they have, so that you can go and start to play with different plug-ins and look into the different kinds of digital signal processing that you want to use for the work you're doing.
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