Audio can be broken. An analogue tape recording can have so much hiss and rumble you can hardly hear what you should hear, a screencast recorded in a room with much ambient noise may sound unintelligible. The good news is that audio can be repaired. There exist a large number of entry-level audio repair applications for the Mac, a considerable number of plug-ins that come with Soundtrack Pro, but few of these repair modules are actually useful to professionals. iZotope RX Advanced is.
Don’t think your recording room is perfectly fit for recording good audio until you’ve been in a radio or broadcast quality sound studio. It’s simply discouraging to see what they have there in terms of sound absorption and contraptions to keep the room absolutely quiet and “sound neutral”. Unless you have a budget that allows you to have such a room yourself, you’ll have to do with less than ideal circumstances.
The USB2200A microphone by sE Electronics I have here in front of me has a pop screen and is firmly attached to a sound deadening mic stand, but behind me there are books, sideways there’s a window and some wood, and behind the microphone there is concrete wall and a computer monitor. It’s hardly the ideal place to record much anything, including voice. In fact, to be honest, I shouldn’t even record screencast movies in this room, but I have little or no alternative, and screencasts are not just fun to do, they also tell more than a written article of ten thousand words.
There are methods to dampen the noise, like surrounding yourself with sound-dead materials (wool blankets, special foam tiles glued to cardboard, etc.) to create an acceptable audio booth inside which you can record your audio, but if you’re also going to record vocals—or other music—you are definitely going to need a proper studio, or at least a room that more or less has the same characteristics.
But what if you really can’t create the proper environment? Or you have analogue tape-based interviews that you have digitised, and which you want to use for a publication? Do you really have to put up with bad quality audio? Not when you have a dedicated audio repair application like iZotope RX—and certainly when you have the Advanced version.
Beware of overzealous repairs
iZotope RX Advanced was the version I could test. This version has two extras which the normal version doesn’t have. The two extra features Advanced offers are especially useful if you’re going to do some serious audio processing. The first feature—Resampling—enables you to change the sampling of a sound file. For example, you have an interview, recorded digitally at 96KHz and 24 bit depth. The resulting file is too big to serve on a web site. With iZotope RX Advanced you can resample the file until it’s small enough to serve fast. The audio quality will suffer, and you will start hearing the equivalent of what we call “jaggies” in an image.
The second Advanced feature—Dither—will allow you to regain some of the original sound quality just as what dithering does to images. In short, Advanced is a good choice when you’re often going to work with sound files that have to be up- or downsampled.
The ordinary iZotope RX application (and the Advanced version) comes with Declicker, Declipper, Denoiser, Spectral Repair and Hum Removal modules. The application also has an equalizer and a gain control. Many of the modules in iZotope RX are also available in sound applications like Soundtrack Pro.
What makes iZotope RX special is the quality of the results you can achieve. This quality comes as a result of extremely fine controls and a better set of algorithms to repair and correct audio altogether. For example, removing rumble (not hum, which is defined as electrical noise) from an audio file is possible in Soundtrack Pro using a denoiser plug-in. If you apply this plug-in, the result will be good enough for most uses, but if you’re after perfection and automation, iZotope RX Advanced’s Denoiser module offers a lot more control over the process, including several different methods, a learning algorithm, and the ability to adjust the removed noise using graphical interface elements that offer real-time feedback.
iZotope RX also lets you compare different settings and batch process several files that have the same problems. It enables you to remove more noise and have fewer side-effects—like the “ringing” sound you can start to hear when you’re overzealous…
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An added advantage of iZotope RX Advanced is that you can use it stand-alone, using its excellent interface—I’ve rarely seen an interface that gives so much useful and usable feedback in real-time, even on my Power Mac G5, and with such intuitive controls given the potential complexity of the task it’s meant to enable. The stand-alone version is just one way of using iZotope RX, by the way. You can also use the plug-in version of this application. The plug-in version will announce itself as a Core Audio component in all Core Audio applications on the Mac. When the plug-in can’t usefully work with the application—like in Logic Pro—it will gracefully quit; it will tell you that it can’t be used in Logic!
I used iZotope RX Advanced to clean up several recordings I made in the past, and which contained many imperfections like pops, hiss, and background noise. I also tried to upsample and downsample a couple of audio files.
After testing iZotope RX Advanced, I came to the conclusion you can work with the RX version without having much knowledge of the program, or even sound engineering, for that matter. It’s that easy to use. However, I also quickly found out that really good results come with learning a bit about audio and audio repair. To that effect, the developers include a great printable tutorial and offer some videos on their web site as well.
After having gone through the tutorial, I could repair some of my files to a level that sounds very acceptable, at least to my ears. Unfortunately, the Resampling and Dither modules were a bit beyond me. After having tried it half a dozen times, I can resample a file, but I’m not sure that I am capable of making it the best possible resampled result—that’s however not iZotope RX’s fault, but my ignorance.
In short, if you care about the quality of broadcast audio, interviews, screencasts, multimedia tutorials and trainings, and podcasts, iZotope RX (265.00 EUR) is a must-have; if you want perfection and the ability to resample audio files with the highest possible quality, the RX Advanced (900.00 EUR) version is what you need.
