Noise Removal

I have in my possession 3 large WAV files recorded from a live show that my friend's band played a couple months ago. The sound quality is very good (right off the soundboard) but there's a high pitched hiss throughout, probably the result of some electromagnetic noise of some type. It's not tape hiss, as the show was recorded via line-in from the soundboard right into SoundForge.

I'd like to remove the noise. I can obviously try to isolate the frequencies and EQ them out, but I don't want to throw the baby out with the bath water. I only gave it a quick shot this morning, and I was finding that with Sound Forge's normal EQ functions, it was tough to strike a balance between filtering out the noise and cutting out too much of the crispness of the drum and vocal sounds.

I was wondering if there are any plugins for SoundForge (or any other standalone programs) that might help me out with this? I do have a short clip of *just* the noise with no other sounds playing... Is there a program out there that can analyze the "noise" part and do some quasi-intelligent filtering of the noise based on that sample? Or maybe some kind of more advanced noise filtering technique I'm not aware of? If I have to just do it with EQ, I think I can dial it in to minimize the impact on the sound, but the noise doesn't seem to be isolated into a very narrow EQ range. Anyone ever had to tackle this problem before?

Greetings!

Yes. There are a few noise filters / analyzers that are add-ons to SoundForge. I have / have used them. If your noise is fairly constant, you can generate a "noise print" from a quiet period on the recording, and use that as a template for the noise reduction. It works quite well!

Audacity has one of these learning noise filters, and it's also open source. Results are okay, but not spectacular.

I've used DNoise with Cool Edit Pro and Cakewalk/SONAR in the past. I played with a few other plugins, but DNoise had the best outcome as far as getting rid of the hiss/pops with minimal impact to the over-all sound quality. Highly recommended.

Great suggestions, guys. I'm gonna try the Audacity package first since it's open source... If the results aren't good I'll give one of the others a shot.

There was a great article about noise removal in DV magazine a while back, which covered all sorts of interesting ways to handle it. I've thrown out that issue, though, sorry.

Anyway, as you've discovered, trying to EQ out a noise throws the baby out with the bathwater. So don't use an EQ to remove noise.

Among the other noise removal techniques is the aforementioned "learn and subtract" filter, where you feed the software a sample of JUST the noise and it goes through and subtracts that from the rest of the recording.

Almost all sound-editing programs should have a subtraction filter like this already in them, including Sound Forge. You probably just haven't found it in the menus yet.

You'll find that these filters can sometimes produce other artifcacts, though, so be careful with them and preview any edits and play with the settings. Different programs are going to be better at noise subtraction than others. The good ones are expensive and use a lot of proprietary code to get the job done.

Ah, here's the DV article I was talking about. It makes you register for an account, but I think that you can feed it garbage for an email address instead of the spam-magnet stuff they want you to put in.