Whether it's for archiving old recordings or restoring master tapes, most studios need a tool that reduces or eliminates unwanted noise from audio files. For that reason, BIAS has introduced SoundSoap (Mac/Win, $99), an inexpensive program designed to remove common artifacts from musical and spoken-word material.
SoundSoap can be used standalone or as a VST and DirectX plug-in. Mac users will need OS X 10.2, and Windows users will need Windows XP Home or Professional. I tested SoundSoap (on a dual-processor Mac G4/1.42 GHz running OS X 10.2.6) as a standalone program, as a plug-in within Steinberg Cubase SX 2.0, and in Digital Performer 4.1 (using FXpansion's VST-to-AU Adapter).
What's the Buzz
SoundSoap's interface is surprisingly simple. The Wash window shows the amount of unwanted audio debris in red and the unaffected audio signal in blue. The Noise Tuner control homes in on the offending frequencies, while the Noise Reduction knob adjusts the amount of noise reduction.
The Preserve Voice button automatically removes frequencies beyond the range of the human voice. When I applied this process to snippets of phone interviews, most of the background noise and hum generated by my cheap Radio Shack phone mic was removed. I wish I had had this capability years ago, because it would have saved me hours of wringing intelligibility from the original sound files.
Additional radio buttons select the listening mode: Off (no noise reduction); On (noise reduction engaged); and Noise Only, which lets you hear only the material that will be removed, so you can avoid losing useful content. The Learn Noise button samples the noise content, and once SoundSoap previews the track, it automatically adjusts the noise-reduction frequency and amount. Giving SoundSoap an area of isolated noise to work on allows the program to get a more accurate reading of the noise content of the file.
The Rinse Cycle
SoundSoap includes buttons for removing 50 and 60 Hz hum, and it has a Remove Rumble button that cuts off frequencies below 40 Hz. Although it didn't remove the hum entirely, the 60 Hz button significantly lowered this artifact on a recording of a Stratocaster that had shielding problems.
Things are a bit trickier when you remove higher-frequency noise with SoundSoap. Use too much noise reduction, and the track will lose its high-end snap and sizzle. Extreme settings will remove attack transients, but that's not always a bad thing. With Noise Reduction full on and the Noise Tuner set at about one o'clock, I was able to transform a mediocre General MIDI 12-string guitar into a very close approximation of a Joe Zawinul lead sound with a hornlike attack. Conversely, I was able to use the Noise Only settings to create the sound of a cheap, phase-shifted banjo from the same file — perhaps not a sound on everyone's wish list, but you never know.
The standalone version of SoundSoap has transport controls for file playback and a small window that indicates the absolute-time location in the file, down to a tenth of a second. Left and right markers select boundaries for processing: you can select in and out points on the fly by typing I or O. The markers come in handy for processing files with multiple, but differing, noise problems.
To finish the job, hit the Apply button to commit your noise-reduction settings to the file. The plug-in version of SoundSoap relies on the host program's transport, selection, and time-display features as well as the host's bouncing resources to process the file.
SoundSoap is not perfect for every noise-reduction application; it is not designed for decrackling or removing pops and clicks. Those who need a broader selection of noise-reduction options may need to look elsewhere. However, SoundSoap does an admirable job of removing hum, rumble, and other relatively steady-state noise. (BIAS recently introduced a high-end version called SoundSoap Pro, which should be shipping in early 2004.)
It is inevitable that removing noise from an audio track will affect the overall sound quality of the material to some degree. Nonetheless, SoundSoap gives you a simple, elegant, and painless way to remove or reduce some of the most common sonic pollutants at a price that won't take you to the cleaners.