60 Hz noise removal

Rick K wrote on 9/24/2003, 11:35 PM
I recorded an urban development team press conference in a church. they fed me a line signal from their sound system which had lots of 60 Hz background. Now I'm editing this 1.5 hour project. I can't bear to turn this over to my customer with all that noise. Is there a way to eliminate or dampen it from the sound track?

Comments

MJhig wrote on 9/25/2003, 11:05 AM
If the Track EQ's 60 Hz Hum notch preset (and variations there of) isn't giving you satisfactory results then Noise Reduction™ 2.0 is your best bet. Actually it's the best choice from the start, even then you may not be able to remove all of the noise.

MJ
Rick K wrote on 9/25/2003, 11:47 AM
I'll give it a try. I had intended to use my shotgun but then the presenters were all over the place, the church sucked up most of the sound and echoed the rest. Since the church had a feed to me, I was forced in a hurry to take it, it was too loud but after they attenuated it, the steady 60 hz noise was obvious. Everything else was just about perfect. Good lighting, good presentation, BUT i was hoping I could remove the noise electronically (having never done this before..hope hope.). I tried the track equalizer which as far as I could tell did absolutely nothing at 60 Hz. Might be useful at other frequencies but of no-use-whatsoever at 60 Hz. You'd think this had never happened to anyone before. I'll try the plug-in you recommended. This video is destined for continous broadcast on the cable channel and I sure as s.... like to get that noise gone. ...no I must eliminate the noise.
MJhig wrote on 9/25/2003, 12:05 PM
>>>>You'd think this had never happened to anyone before<<<<<

This happens all the time, especially with folks doing video. Audio is MUCH less forgiving than video.

Just as much care, if not more must go into capturing the audio as the video. Fixing audio after the fact should be considered "impossible" so that sound checks become as important as lighting etc.

Unfortunately the real world is not like those forensic shows on TV where they remove everything from a mini-cassette internal mic, ninth generation mono recording but the sneeze of the suspect from across the room providing an incriminating voice print along with the cattle yard sounds giving away the kidnapper's location.

MJ
Rick K wrote on 9/25/2003, 5:46 PM
yeah...but...it seems like a pure 60 hz buzz should be removable. And yeah, I'm learning. It was forced on me at the last minute. I seem to learn better from mistakes.
Chienworks wrote on 9/25/2003, 5:57 PM
The problem is that it's not pure 60Hz. AC line noise usually includes several strong harmonics at 120, 180, 240, at 480Hz as well.
Rick K wrote on 9/25/2003, 6:23 PM
I wondered if that wasn't the case. Tried using Vegas to get rid of it. Then I tried harmonics at 120, 180 etc. Nope. no noticable difference. Chienworks, any experienc with noise reduction 2.0 plug in? It's kinda expensive for a one shot use. If it will help, I may be able to induce the project to buy it.
LarryP wrote on 9/25/2003, 8:22 PM
I bought Noise Reduction because of a similar problem with some unbalanced equipment and it saved a live recording session. One tip is to use 2 or 3 copies of Noise reduction with the same noise print instead of one large hammer.

Where ever possible use balance audio and carry a direct box and some adapters just in case. It's not very expensive and might help.

Yes Noise Reduction is expensive but I didn't have an option to redo the recording. Besides it works wonders on the motor noise the mic on my camcorder picks up.

Larry
Chienworks wrote on 9/25/2003, 8:34 PM
Well, i don't really advocate this as a regular thing, but you do get a 15 day free trial if you download the demo of NoiseReduction. If this is really a one-shop thing then go for it and see how it works. Just remember it next time you need it and maybe those who are wanting your services can help underwrite the cost.

The nice thing about NoiseReduction is that it's much more automatic than methods using EQ. You simply find a spot with just the line hum and nothing else (even a second's worth is plenty), highlight it, and let NoiseReduction analyze it. It can then subtract that sound pattern from the entire file in one step. It's probably one of the most "miraculous" things you'll ever see happen on a computer!

Also included are a few other tools that are very handy when working with old records and similar sound problems. Last night i transfered a 30 year old LP recording of a friend's old college choir to CD. The pops and crackles in some places were 20dB louder than the music. One pass through Click and Crackle Removal and the recording sounded like new! If you need that sort of thing now and then the price is well worth it.
Rick K wrote on 9/25/2003, 11:17 PM
Thanks. we'll give it a try and find out.
JonnyMac wrote on 9/27/2003, 11:31 AM
Yes, it's expensive but wow, what a great product. I removed noise similar to what you're experiencing from a clip with NR and am thrilled that I spent the money.
Rick K wrote on 10/3/2003, 6:49 PM
Ok..I got the software but I'm a little confused how this stuff works. Any sugestions ..like a few words. How do you take out 10 Db twice?
LarryP wrote on 10/4/2003, 5:36 AM
Set for 10 db, take a noise print and save it as a preset (the little floppy disk). Then add a second copy of noise reduction to the fx chain and select the preset you just saved from the preset pull down.

If you get too much gating (dropouts) on quiet passages try adjusting the little down arrow, just a little, in the lower left corner of the "noise print" tab.

That should do it.

Larry
Rick K wrote on 10/4/2003, 6:38 PM
thanks,
my PCs down with funny problems, Hopefully I'll try it out this weekend.
R
Rick K wrote on 10/6/2003, 10:37 PM
boy am I stupid. This doesn't seem to do anything. larryp can you help me with this?
RBartlett wrote on 10/11/2003, 2:49 AM
Make sure you add the SonicFoundry filter to the audio by dropping it on the section you need, or possibly the output bus if it is all goofy and you aren't adding additional audio.

NR2 in demo mode seems plausible especially if you are a not for profit org.
I've considered www.bias-inc.com's SoundSoap, but I don't have XP and am not brave enough to buy it ($79 in US, £99 in UK, what a rip off!) with the supposed GDI+ patch from Microsoft to get it to work. Bias are still evaluating if this works.... perhaps not the best outfit.

Otherwise the "make your old records into CDs" brigade might help for less than the outlay for NR2.

SoundForge (full) and NR2 was a good bundle, but that stopped with SF7.
Electronic Software Download is another important characteristic of DX filters, for me.
Rick K wrote on 10/11/2003, 2:51 PM
I bought NR2 and it helps but it isn't enough. I've been reading Jay Roses book. He talks about the 'comb' filter to remove 60 Hz noise. He also makes the point that there is little useful sound below 100 Hz so this is usually dropped out during voice recording meaning the 60Hz would go away. Don't notice and difference when I try to do this. Then he talks about copying the track and shifting it 16.3 ms. when played at the same time as the main track the 60Hz peaks are negated and their harmonics. I don't how to shift the audio track less than 1/30 of a second in Vegas to do this. Seems plausable though. THis is snowballing.
Chienworks wrote on 10/11/2003, 4:45 PM
avideo, turn off "Quantize to frames" under Options. This will allow you to move the audio track by tiny amounts.
soundtree wrote on 10/14/2003, 5:06 PM
if you have dsl or faster and Icq you can send me a copy of the file and i will fix it for you.