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Barbelith digital audio gurus, please help

Disco is My Class War

13:34 / 30.10.06

I recorded some interviews for a big research project recently. One of the interviews took place in a very noisy cafe, and the sound recorder I was using recorded a lot of noise, so much so that when I play it back I'm having difficulty distinguishing the informant's voice from the other people in the cafe, the coffee grinder, the music etc.

Well, now I get to transcribe the darn thing. I've been using a freeware program called Audacity to clean it up, but with little success. I've even tried adjusting the graphic equalizer in Winamp to isolate the voice, but even with the voice isolated, I'm only getting about 50% of what the person actually said. And the voice tracks on the recording are all at around the same frequency, making GE calibration tricky. Or so it seems.

Does anyone have suggestions for software I might use, or how to fix this? There are heaps of audio restoration programs out there, but not many that focus on voice recordings; most are for restoring old LP's. Those that do seem to be designed for forensic analysis and cost the earth. So, anyone know a PI or a cop who can get me a copy of some l33t noise removal software?

ONLY NICE THINGS

13:54 / 30.10.06

How big is it?

14:15 / 30.10.06

Perhaps you've seen the Transom.org site? If not, it does have some tutorials on Audacity as well as ProTools, which has a free version. Not sure if this is any help, but good luck.

15:08 / 30.10.06

If you have a good-sized chunk of "room tone" -- the ambient sound of the room without too much crashing or clinking or punctuation going on, you can try copying that chunk, pasting it onto a new track, looping the new track under the existing track, and inverting the wave form. (should be a control to do that somewhere in Audacity).

What this'll do is cancel out that ambient sound, leaving you with whatever isn't that ambient sound. (Including clinks and clatters, but also hopefully human speech.)

I'm not sure, however, that this is exactly your problem. The only other things I could suggest would be EQing the voice as precisely as possible and deleting everything that isn't it -- by "deleting" I mean moving the frequency faders to the bottom of the EQ panel. This is another way to eliminate things that aren't that voice.

It does sound like you've got the problem of many voices, though, all of which are probably going to show up in about the same spot in the EQ, which will make separating them out a real chore.

I suppose the only other option is to see if you can make the voice disappear and then do the opposite (copy & paste voiceless waveform onto new track, invert it, line up with existing voiced track and see if that disappears all non-voice material).

Disco is My Class War

00:32 / 31.10.06

Haus, it's about 60 MB as a wav file, less if I use the mp3 version.

MattShepherd suggested Cool Edit Pro's noise reduction tool, which I may try today. And if I can work out esactly what you mean by inverting the track, I'll try that too, grant

02:30 / 31.10.06

I can only tell you that the command is usually "invert" and that it flips the visual display of the waveform upside down. I'm relatively certain that's how Cool Edit removes noises as well, only automated.

Scrambled Password Bogus Email

08:36 / 31.10.06

I believe grant is referring to reversing the phase. If you take two identical, or at least very similar, sound sources, reverse the phase of one and then paste them together, any matching signal where the phases are inverted relative to each other will completely cancel each other out.

If you can host the sound file somewhere, I'll DL it and run it through the machines here later tonight.