BIAS SoundSoap Pro (Mac/Win)

Audio restoration software, which analyzes a digital file in an attempt to isolate and remove unwanted clicks, pops, and broadband noise such as tape hiss, is one of the little miracles of digital audio. Cleaning up old or flawed recordings, however, is still more art than science, despite the long strides that have been made in the technology of restoration software. (The programs may be miracles, but

Audio restoration software, which analyzes a digital file in an attempt to isolate and remove unwanted clicks, pops, and broadband noise such as tape hiss, is one of the little miracles of digital audio. Cleaning up old or flawed recordings, however, is still more art than science, despite the long strides that have been made in the technology of restoration software. (The programs may be miracles, but they're not magical.) In addition, there is a gap in the affordability range of such programs: there are either high-end suites with multiple DSP noise reduction tools or entry-level programs such as BIAS's SoundSoap. (For a review of SoundSoap version 1.1, see the February 2004 issue of EM online at

BIAS now has filled that gap with the release of SoundSoap Pro, a serious restoration plug-in designed to handle the most common noise-elimination problems. Priced at an affordable $599, SoundSoap Pro provides a professional set of tools — including Hum & Rumble, Click & Crackle, Broadband, and Noise Gate modules — for dealing with old or unexpected noise. The modules operate together or independently, which helps save CPU cycles.

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FIG. 1: SoundSoap Pro''s Launch screen provides helpful text on the operation of the plug-in.

Liquid or Powder

SoundSoap Pro is compatible with most major plug-in formats, including VST, RTAS, DirectX, and AU. (There is no MAS version, but I used the AU version in Digital Performer 4.12.) Mac users will need a G4 or G5 (a 500 MHz processor is recommended) with OS X 10.2 or later. A Pentium III or 4 running Windows XP is required for PC users. BIAS recommends an 800 MHz processor.

The installer program will deposit all of the disk's plug-in versions in the proper folders on your hard drive. Then you begin the authorization process, a straightforward if annoying chore. The program comes with a BIAS Key, which is a small dongle that lights up when properly inserted in a USB port. With the key in, you can launch an included control panel that prompts you for your copy's serial number. Entering it gets you a version of SoundSoap Pro that lasts for 14 days.

For permanent use — and an authorized BIAS key that you can then use on any computer with a SoundSoap Pro installation — you must also obtain an authorization code from BIAS's Web site. It's best to register immediately, and the panel makes it easy (assuming you have internet access on your studio computer) to go to the web site, register, obtain your authorization code, paste it into the proper field in the control panel, and begin working. (If you don't have Internet access, you can obtain your code by phone, fax, or mail.) With the plug-in authorized, SoundSoap Pro will appear in the list with other plug-ins of the same type within your digital audio application.


When you first call up SoundSoap Pro to process an audio track, you'll see the Launch Area of the plug-in. This area contains some helpful text with an overview of the plug-in's four modules, displayed as tabs at the bottom of the window (see Fig. 1). Each tab can be enabled while any or all of the others are disabled, saving processing power. Each plug occupies a logical place in the chain of tabs from Step 1 to Step 4.

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FIG. 2: The Hum & Rumble tab allows for control over low- frequency noise in a range from 20 Hz to 500 Hz.

BIAS recommends working from left to right according to the order of the steps, because it's more efficient and easier, for example, to deal with Hum & Rumble first before proceeding to Click & Crackle. Next you can manipulate broadband noise and finally employ a gate for a set noise floor. If used properly you'll get a much cleaner track, especially if your noise problems are easy to isolate.

Within each tab, a versatile set of controls is present. The Hum & Rumble Window (see Fig. 2) is designed to deal with hum typically centered at 60 Hz and below and usually caused by bad wiring or improper grounding. Sliders provide control over filter width (Q), depth, and frequency parameters (between 20 and 500 Hz) and up to 10 harmonics as well as subsonic rumble. The Click & Crackle Tool (see Fig. 3) helps you isolate annoying transients (such as those on vinyl records) and static-induced pops and crackles. That tab's two threshold sliders control the degree of noise reduction.

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FIG. 3: The Click & Crackle tab has settings designed to eliminate transients (such as those found on vinyl records) and other sources of pops and static sounds.

All settings can be stored and recalled from disc, and four Compare settings are available in RAM. Every tab provides a useful waveform display for comparing the input and processed signals. SoundSoap Pro's Noise Only option is where you find the real dirt on your sound files. Engaging the button isolates the noise that you've analyzed, which is a great way to ensure you're not throwing out the music baby with the noise bathwater.

Scrubbing Bubbles

The Broadband tab (see Fig. 4) is where you control sonic infestations such as tape hiss, tire noise, wind, HVAC noise, fluorescent lighting noise and other continuous broadband problems. The module operates across 512 distinct audio bands (controlled by 12 threshold and reduction sliders that can work independently or as a group) and supplies knobs for attack, release, and tilt, which allow you to shift the targeted noise bands toward lower or higher frequencies.

As with other restoration programs, SoundSoap's broadband module “learns” the characteristics of the noise you want to eliminate. You play back a section of the audio file where noise is isolated and press either an instant or timed learn button. The plug-in responds with a noise reduction curve that you can then fine-tune with 12 blue threshold sliders or 12 yellow reduction sliders. After the plug-in chooses the set of frequencies to be eliminated based on what it has learned, you can press the Noise Only button to hear them. If you hear any music mixed in with this noise, you can adjust the threshold and reduction sliders up or down individually or in a group to make sure no discernible tones are being cut with the noise. That balancing act is essential to avoid winding up with a track full of digital artifacts.

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FIG. 4: The Broadband tab contains the Learn button, which takes an instant or user-defined measurement of designated consistent noise such as tape hiss. Visible under the plug-in are the original test track that was imported from DVD and the same track after processing by the Noise Gate module.

SoundSoap Pro's last stage is its Noise Gate tab (see Fig. 5), which provides standard threshold, attack, and release controls. The gate can also be used creatively to generate extreme special effects. In all tabs, a real-time spectrogram enables visual monitoring of noise; the spectrogram's color-coding can help you locate necessary adjustments and see the results immediately. You also get thumbnail views of the other tabs' status when one is active. The plug-in has Bypass buttons for each tool and a global bypass button.

Stain Lifting

After installing SoundSoap Pro on my system (a dual 2 GHz Mac G5 running OS X 10.3.5), I was eager to try the Broadband tab for eliminating broadband noise. I needed a noisy audio track to load into Digital Performer. (The SoundSoap Pro CD has example audio files to use with the tutorial in the product's manual.)

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FIG. 5: Pictured above is the Noise Gate tab with a graphical display of imported audio before processing.

I happened to have a DVD of the Marx Brothers film Monkey Business in my computer. The audio track of one scene offers not only a typically noisy 1930s-style soundtrack, but it also offers an even older (and noisier) gramophone track! That would surely constitute a trial by fire for SoundSoap Pro.

I imported the audio track into Digital Performer (DP). On the clip (see Web Clip 1), an exasperated Customs agent faces Harpo Marx and suspiciously demands, “Chevalier, eh?” There's a pause that's full of soundtrack noise as Harpo cranks the gramophone, which then plays while he mimes the French musical star Maurice Chevalier.

I positioned DP's cursor to begin playing at the beginning of the soundtrack noise, and then pressed the button with the clock icon next to SoundSoap Pro's Learn Noise button. I pressed Play in DP. At the end of the soundtrack noise and before the gramophone noise, I pressed the clock button in SoundSoap Pro again to halt the learning process. When I played back the same section, SoundSoap Pro applied its noise reduction algorithm to the frequencies it had analyzed.

The results were astonishing, but not for the reasons I thought. The noise between the Customs agent's question and the gramophone was completely gone (see Web Clip 2). There was also a smooth transition from the agent's speech to total silence and from silence to gramophone. However, it was not SoundSoap Pro's broadband tab working this magic, but its noise gate section. Before fully reading the manual, I assumed that an “x” meant “off” in a tab's checkbox, and I had the Noise Gate's box checked. Still, that exercise demonstrated the accurate learning capabilities of the plug-in and the useful parameter presets in the Noise Gate tab.

With the Broadband tab properly activated and other tabs bypassed, I performed the test again. This time, as you might expect, SoundSoap Pro produced a more subtle noise curve. I used the yellow reduction sliders to create a modified soundtrack with a lower level of ambient noise between the Agent's speech and the gramophone in the example (see Web Clip 3). With the broadband test, the plug-in's Noise Only button was crucial for understanding what the analysis did to the soundtrack. Since the first analysis included some of the dialog and music tones in the noise (see Web Clip 4), I used the sliders and the plug-in's Tilt function to create a final noise profile (see Web Clip 5) before bouncing the processed clip to a new track.

I checked out the Hum & Rumble and Click & Crackle tabs by mixing buzz, pops, and static from an unplugged guitar cable with a prerecorded track to create a file with noise problems more typical of a project studio. The plug-in was able to handle these basic problems well, depending on the level and consistency of the offending noise. In many cases, isolated clicks and pops are easily handled by basic digital audio editing tools, and low-frequency hum can be controlled by high-pass filters — if it's not out of control to begin with. That's the important thing to remember about software of this type. Although SoundSoap Pro can make your garbage cleaner, garbage is still garbage. The best way to control noise is at the source, before it ever arrives on disc.

Stronger Than Dirt

SoundSoap Pro is an excellent alternative to high-priced digital audio restoration suites. BIAS's plug-in has a complete set of tools that will appeal to the pro or project studio owner whose business involves making the most of bad recordings or transferring vinyl records to digital. And of course, even pros sometimes get caught making bad recordings — for example, in the field, where noisy traffic or wind doesn't seem to be a problem until the track is back in the studio.

Novices will need to pay attention to the plug-in's manual, which includes valuable information on types of noise reduction in general and clearly explains the plug-in's sometimes less-than-intuitive operation. But SoundSoap Pro is an ideal tool for most common problems in tracks that can't be rerecorded. When a track is sick with noise, SoundSoap Pro has all the surgical tools necessary to determine if the patient gets a clean bill of health or needs a dirt nap.

Rusty Cutchin is an associate editor of EM. You can reach him


SoundSoap Pro

audio restoration software


PROS: Multiple tools and parameter settings for various noise-control problems. Timed or instant noise analysis. Noise-only playback. Tilt function for fine-tuning noise curve. Modules work either independently or collectively.

CONS: Has a cluttered interface in Broadband tab.


BIAS (Berkley Integrated Audio Software)