Cleaning up Microphone Static

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Sir Shockwave
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Cleaning up Microphone Static

Post by Sir Shockwave » Tue Apr 17, 2012 10:14 am

Me again. I apologies if you get this question a lot, but I'm having no luck cleaning up Microphone Static from the recording. I've tried running the De-Noiser, but it doesn't seem to have much of an effect beyond near muting the vocals.

Does anyone know how this can be removed in Audacity 2K?

steve
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Re: Cleaning up Microphone Static

Post by steve » Tue Apr 17, 2012 11:50 am

Does the blue waveform touch the top/bottom of the track? If it does, then the recording level was too high and the "Static" is distortion (clipping). Sadly clipping/distortion is virtually impossible to remove. If you don't think that is the problem, please post a short sample (just a couple of seconds in WAV format) for us to have a look at.
See here if you need help uploading an audio sample: http://forum.audacityteam.org/viewtopic ... 49&t=64936
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Sir Shockwave
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Re: Cleaning up Microphone Static

Post by Sir Shockwave » Wed Apr 18, 2012 9:49 am

Here's the Microphone test I ran. The blue wasn't tapping the edges, but if you listen, well...
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test.wav
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solanus
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Re: Cleaning up Microphone Static

Post by solanus » Wed Apr 18, 2012 4:26 pm

Well, your original recording level is fairly low, so it's not distortion, it's background noise.
Are you sure you are using Noise Removal correctly?
You need to first have it learn what the background noise level is, and then remove it from the entire wave, like so:
1. Select a section of the wave that is just background - something that should have been silent if the recording had been perfect (the first 0.35 seconds of your example).
2. Choose Effect>Noise Removal. Notice that the dialog has a Step 1 Get Noise Profile - when you click on that button it will "read" the noise from that short selection, and the dialog will disappear. No actual noise removal has occurred yet.
3. Select the entire wave and again choose Effect>Noise Removal, but this time do step 2: Just click OK. This will remove the background noise and leave the vocals alone for the most part.
This will still leave some artifact noise, but it will be much better, and you can keep repeating Step 2 to further clean it up.

Also, before you start, you may want to Normalize your wave to get the max volume out of it.

steve
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Re: Cleaning up Microphone Static

Post by steve » Wed Apr 18, 2012 4:31 pm

Wow that's weird.

It's not "distortion". There's quite a lot of "hiss" noise, plus there's a peculiar "squeaking" sound.
It is visible in the first half second of that clip (before you start talking) if you set the track to Spectrum View
squiggle.png
squiggle.png (149.84 KiB) Viewed 12443 times
It's interference of some sort and attempting to remove it is likely to cause a lot of damage to the sound that you want to keep.
What was that recorded with? A headset mic plugged into your laptop? Laptop internal microphone?

It may be caused by electrical interference if you're near a strong interference source (such as electrical equipment or radio transmitter) but I think the most likely cause is that you need to invest in a better sound card or a USB microphone (though this need not be expensive - the Logitec USB desktop mics are only about $20
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steve
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Re: Cleaning up Microphone Static

Post by steve » Wed Apr 18, 2012 4:36 pm

The "squiggle" is only in the left channel which means that interference from an outside source is unlikely to be the cause - it's most likely just a poor sound card.
If you split the track (click on the track name and select "Spit to mono" then delete the left track, the noise removal effect will work better on the remaining (previously right channel) mono track. (though I'd still recommend upgrading the hardware as a better long term solution).
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