[2.0.2/Win] Tips on cleaning up audio?

[Shohreh]

Hello

Here's a sample of crappy audio from a conference that someone recorded with a camcorder with the built-in microphone.

Out of curiosity, can Audacity clean up the sound a bit (eg. removing echo, lowering audience noise, etc.), or is it beyond repair?

FWIW, VLC says that the MP3 file is "Stereo 22050Hz 64kb/s": I'm not sure how to find the sample size (16 bits?) and the sample rate for each channel?

Thank you.

[kozikowski]

You almost have all four. We can't do anything about echoes (1), we can't slit up a recording into individual performers - background sound (4) and we can't do anything about compression damage (3).

The Four Horsemen of Audio Recording (reliable, time-tested ways to kill your show)
-- 1. Echoes and room reverberation (Don't record the show in your mom's kitchen.)
-- 2. Overload and Clipping (Sound that's too loud is permanently trashed.)
-- 3. Compression Damage (Never do production in MP3.)
-- 4. Background Sound (Don't leave the TV on in the next room.)

If you can find somewhere in the show where one of the performers got really loud and overloaded the track, that's (2).

Koz

[Shohreh]

Thanks Koz for the infos. I tried Effects > Noise Reduction, which is pretty nice with its default settings but I was wondering if something more could be done, either by playing with the Noise Reduction settings or some other item in the Effects menu?

Here's a sample after using Noise Reduction.

Thank you.

[kozikowski]

Noise Gate tries to suppress any sound lower than a set value.

http://wiki.audacityteam.org/wiki/Nyqui ... Noise_Gate
http://wiki.audacityteam.org/wiki/Downl ... g_Plug-ins


I guess we never wrote anything on Noise Removal settings.

Noise Removal tries to subtract whatever is in the profile you captured from wherever you apply it.

-- Noise Reduction is the amount of affect. Zero and it doesn't do anything.

-- Smoothing affects how much voice is intentionally missed in the reduction. Too low and voices become distorted and honky, too high and reduction becomes sloppy everywhere.

Attack and Decay affect reduction just before and after words.

This latest Noise Removal works by assuming nobody notices noise during speech, so it doesn't try. What usually happens in heavily noisy performances is you can get silent backgrounds and noisy words. If you try to process the words, they start getting science-fictiony and garbled.


There is a serious discussion to stop calling it Noise Removal and start calling it Noise Reduction. It's' highly unlikely to ever actually Remove Noise.

Koz

[Shohreh]

Thanks for the info on using Noise Gate. I guess it's a new plug-in, different from the Effect > Gate by Steve Harris that ships with 2.0.2.

[kozikowski]

If you ever watched/listened to Rachel Maddow, she has a Noise Gate on her voice.

Podcast:
http://www.msnbc.msn.com/id/26315908/ns ... ddow_show/

She has, as she puts it, a crappy cable news show, so even though it looks like a studio, it's actually a large noisy room and you regularly hear people drop stuff and talk during the show. If you listen carefully when she stops talking, the gate waits a very brief second and kills the "studio" sounds. It's like everything she says has a little "tail" on it. Fortunately, she has a clear voice, so they can get away with that.

This only started happening the last month or so, so it could change. Somebody cottoned to the fact that a serious news show should not sound like it was recorded in my kitchen.

Still no substitute for a good recording.

Koz

[kozikowski]

I think Steve wrote this one. He's a senior forum elf.
Koz

[Shohreh]

Yes, Noise Gate (release 3) is from Steve Daulton.

I'll experiment per the enclosed noisegate-help.txt and see if I can get rid/lower the background noise made by the audience.

Thank you.