Ray Gun

Zap!
by
Read G. Burgan

I don't suppose I was more than seven or eight the Christmas I got my Buck Roger's ray gun. It brought many exciting hours into my life as I and other neighborhood kids played space cadets, 1950's style.

It took a lot of imagination to believe that the glorified plastic flashlight with it's color filters and hooky sound was really a ray gun. But imagination comes easy to an eight year old and you'll have to take my word that I single-handedly made our planet safe for another generation by destroying numerous colonies of space aliens.

Once again I have a ray gun. This one is made by Arboretum Systems, Inc. and is a software that promises "Just point and shoot: Ray gun will search-and-destroy the noise in any sound file, automatically."

As you might guess, I'm no longer eight years old and my imagination needs more than slick copy to persuade me of a product's virtues. So I set off to see for myself what Arboretum's Ray Gun could do by testing it's tools against other standard noise reduction software.

Ray Gun comes in two forms: A stand-alone version that you can use by itself, and a DirectX plug-in version that will work with any program supporting DirectX plug-ins. It will run on either Mac or a Windows 95 platform.

The first thing I look for in any digital audio noise reduction software is an impulse filter for removing pops and clicks and a broad band noise filter for removing continuous noise. Ray Gun has tools for each of these functions.

First, the Impulse Noise filter. Arboretum's goal is to provide a simple, uncomplicated means of digital noise removal. And the Impulse Noise filter's operating interface is as easy to use as you can possibly get short of eliminating all controls.

It has just one lever marked "Pop". This level controls the sensitivity of the impulse filter on a scale of 0 to 100 percent. You place the plug-in in the Preview mode and move the lever until the program material starts to distort, and then back it off until it no longer distorts. Then you run the filter.

How effective is this simplistic approach to removing pops and clicks? I compared it to the software I usually use, and found it to be quite close in it's results. It was surprisingly effective at removing pops and clicks from various vinyl sources. I would rate it as an A-.

Before we look at Ray Gun's Noise Reduction tool, we need to define some terms. Most broad band noise reduction software works by having the user select a non-program portion of the sound file (For example, the silent portion between words or the silent portion between cuts of a record). Any sound in this sample should represent the noise present in the sound file. The noise reduction software than takes a "snapshot" of this noise and creates a filter that is designed to fit that precise snapshot.

Most noise reduction software has several onscreen controls that adjust parameters like the attack and release time, degree of noise attenuation, etc. One software I use has seven adjustable parameters plus the ability to individually adjust the shape of the filter at more than 2,000 individual points in an x/y graph setting. This creates a filter that "fits" the noise profile like a glove, and can result in a very quiet recording -- even from one that seemed impossibly noisy.

In an effort to maintain their commitment to a software that is user friendly, Aboretum uses a different approach. Instead of creating and applying a noise print, they use dynamic noise filter.

What is a dynamic noise filter? Perhaps the most famous example is the old Burwen laboratories hardware dynamic noise filter that was quite popular among audiophiles in the 1970's and sold in a number of formats including the KLH 1201A Dynamic Noise Filter.

Essentially, these are downward expanders. You establish a threshold for noise, and everything below that threshold is considered noise and is expanded downwards. As an additional step in increasing the effective noise reduction, a filter is applied to the low level signal (noise), but not to signals above the threshold (music). The assumption is that the psycho acoustic phenomenon of masking will cause the noise to be inaudible when the program material is present. In practice, this works out better with music than with the speaking voice. Aboretum carries this one step further by using a software that continuously evaluates the noise and applies a 512 band filter to more effectively reduce the noise.

The advantage to this approach is simplicity. In Aboretum's case, Ray Gun has only two controls: Threshold and Attenuation. The software automatically sets the threshold of the filter. The threshold control is simply an additional means for the user to fine tune the effect. Attenuation controls how much the noise is attenuated -- up to a maximum of 36 dB.

The problem is that you trade off effectiveness for simplicity. While dynamic noise filters have a place -- and were a welcome analog addition in the days before digital audio processing -- they are limited in the amount of noise they can remove.

In testing Ray Gun, this limitation was quite apparent. Ray Gun's Noise Reduction filter does remove noise. But it is not able to eliminate all audible noise. If you are using a fairly clean vinyl LP or a tape with only a moderate degree of hiss, you might find it's noise reduction satisfactory.

But if you are looking to seriously clean up analog material with continuous noise problems, you will probably want to look at one of the several noise reduction packages that uses a true noise printing approach. I would rate Ray Gun's Noise Reduction filter a C-.

Ray Gun also includes a filter tool using notch filtering techniques to remove either 50 or 60 cycle hum and rumble. The operating manual does not indicate what settings each filter uses, nor are they user adjustable. They are either on or off.

In applying them to recordings needing notch filtering to deal with rumble and hum, they did reduce the low frequency noise. But since they aren't adjustable, their application is limited. I would rate these filters as a B-.
Arboretum's Ray Gun is designed for a person who doesn't want to be bothered with the nuisance of setting parameters and learning new applications. Ray Gun meets its stated goal to provide a user friendly package that will provide a moderate amount of noise reduction with virtually no user intervention.

If you don't already have any noise reduction software and want a basic noise reduction package that will require no learning curve, then the stand-alone version of Ray Gun may be just the ticket for you. The suggested retail price is $99. Arboretum Systems, Inc., 915 Cole St. Suite 387, San Francisco, CA 94117. (415) 626-4440 FAX (415) 626-4439 http://www.arboretum.com info@arboretum.com.

-- The End --

Read Burgan is a free lance writer and a former public radio station manager who can be reached at (906) 296-0652 or through e-mail at rgb@up.net.