The Audacity of Open Source Audio
The Audacity audio editor is a great program. Take that as you will: It's truly functional software. It's a great illustration of the power and versatility of open source. Audacity has been an active project for some time. But because it provides an esoteric service, it was only recently I had reason to sit down and use it.
Due to microphone-support issues in Linux, and a Windows machine that has trouble with its own weight, never mind throwing sizable files in the mix, I've used Audacity 1.3.5 on two of the three supported platforms. There are differences in feature set-up, not function. After a learning curve of two hours came weeks of declaring my undying love for the project to anyone who'd listen.
Never having worked with audio files for anything other than converting formats, using Audacity for the first time was intimidating. It wasn't necessarily the layout, or the fact that the Audacity project makes it clear that the beta version is not fully documented. It is apparent upon launching Audacity that this application has many features, and many of these features are heavy with audio-editing terminology.
I am, obviously, then, not someone who has ever worked in a recording studio. I can't say, for sure, how Audacity compares with software used in professional environments. I can say without reservation that Audacity offers more features than I will likely ever need editing the audio files I need to edit. The tools for silencing ambient noise, combining, cutting, moving, and mixing tracks are first rate. Would professional musicians use Audacity on a regular basis? I couldn't tell you. Would a media department in a corporate environment that needed to produce quality sound files for advertising, presentations, or promotional purposes find this useful? Without a doubt, Audacity would be all they'd need.
As mentioned previously, Audacity is a cross-platform open source program. It is able to run on Windows, Linux and Mac systems. Though enabling certain features differed between the Windows and Linux versions, neither was difficult, and both worked flawlessly once configured. In both cases, MP3 import/export functions needed special attention, due to the licensing/patent restrictions on the MP3 format. Installing LAME prior to installing Audacity on Linux (though some distributions include LAME as an Audacity dependency, others do not) is usually all Audacity requires to associate the exporting/importing tools with the appropriate library. Windows requires the lame_enc.dll file be present on the system, and that Audacity is directed to it through the preferences dialog. Macs require a similar process (though the appropriate library is different) to incorporate MP3 functions.
Naturally, much of the recording quality comes from the hardware (and, I've discovered, the location of the hardware) used, rather than the software application. Still, even the best hardware in a decent location can pick up unintended noise. Tracks may need leveling, compressing, or equalization.
Noise removal is very useful, and perhaps the easiest to use effect that produces the most dramatic result. Once a track is recorded, select a few seconds of silence from the track (or as much silence as possible up to this point), choose the Effects menu, and click the Noise Removal option. A dialog will appear, and since the silence has been previously selected, clicking "Get Noise Profile" will return a result that should minimize ambient noise sufficiently (though the user is able to change these settings). It's easy to apply to the whole track by exiting the dialog, clicking Edit, and Select All, and then entering the dialog again (there is no need to recalculate the ambient noise, as Audacity saves this profile and associates it with the track).
Other effects allow users to add reverb, echoes, and generate tones, clicks and silences. I've never had issues importing tracks with different bitrates and sample rates into existing projects, and aligning tracks is as visual an experience as it is an audible one. The Audacity toolbar allows for quick sliding/placement of tracks (double-ended arrow), and track selection, even across multiple tracks (the I).
Audacity can be enhanced with plugins, and being open source, these plugins are encouraged (and are occasionally added to the main project). Naturally, there are other ways to get involved with the project, even if programming or a Google's Summer of Code Project isn't your forte. Audacity seems particularly eager for people able to help translating their documentation and website into other languages, as well as offer foreign language support.