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Adobe Audition Saves the Day

Frequency Space Editing solves a nasty problem

By Frank Moldstad

Frequency Space Editing workspace in Adobe Audition 2.0

What do you get when you closely mic an acoustic guitar that needs some setup work, playing a piece with sliding chords? A chorus of squeaks and buzzes to accompany the guitar. That's what I was faced with recently, and the prognosis was grim.

I tried EQing the unwanted sounds out, which didn't work because they spanned the guitar frequencies. I tried zooming into the waveform recording and deleting the noises, but that proved impossible -- not only were they hard to find, they were joined to the music in such a way that I couldn't delete a squeak without snipping off the beginning of a chord.

But something had to be done, because the acoustic guitar part was played solo for four bars at the beginning of the song before the band entered. In the track's current form, that would be unacceptable. The microphone, an Audio Technica 4050, had been positioned about four inches from the neck, aimed at the 12th fret -- capturing the Martin guitar's warm tone along with all its extraneous noises. These distracted from what was otherwise a beautifully played part by guitarist Darryl Marini.

It looked as though the whole track would have to be re-recorded. There was just one more thing to try -- Frequency Space Editing in Adobe Audition. I've used this successfully in the past for removing single events from a track, but never for a recurring problem throughout an entire track. I was dubious, because there was such a wide variety of stuff to be removed. The moving chords generated noises on the low E and A strings that sounded like a boat tugging on its mooring. The high E and B strings made sounds like small springs being released in the background. As the sliding chords moved up and down the neck, the noises followed across the frequency spectrum.

Workspaces

After importing the guitar track into Audition, I opened the Frequency Space Editing workspace by selecting it from the drop-down menu at the top right of the interface. Then I hit play, and almost immediately there was a prominent squeak. This one was easy to spot in the Wave file because it was all alone.

To erase it, I selected the Marquee Selection tool from the top left of the interface (it's the icon that looks like a box). This and the Lasso Selection tool (rope icon) are the two main Frequency Space Editing tools for isolating unwanted events. The Lasso Selection tool is for irregularly shaped events, and I would need it soon enough. But it was simple to draw a rectangular form around the first squeak with the Marquee tool. Then I hit the delete key and the squeak was gone, leaving a black hole of silence behind.

First noise, ready for deletion.             Gone!

 The Frequency Space interface lets you see not only where audio events are on the timeline, it also shows you where they are in the frequency band. The interface is essentially a graph, with the horizontal (X) axis measuring time and the vertical (Y) axis measuring frequencies. High amplitudes are represented by brighter colors -- the default view ranges from dark blue (least amplitude) to bright yellow (most amplitude). You can customize these colors as you wish, and there are also nine preset views.