Getting rid of "hum" in sound background

Kinoko · Sat 22/10/2005 12:19:27

I'm trying to create a sound file of footsteps walking on grass/ground and I recorded this, and it's pretty damn perfect for what I want. The only problem is that I can't get rid of that "hum" in the background. I tried playing with the equalizer and stuff in Gold Wave but I really have NO idea how to manipulate sounds... does anyone know if/how I can get rid of it, so the atual "footsteps" are the -only- sound?

The file: http://kinoko.futariba.com/misc/walking2.wav

Nikolas · Sat 22/10/2005 12:21:46

I think that EQ or a band pass are your best bet. Also a denoiser would work. I don't know if you have all these plug-ins but I'll try to do it here in my studio.

I heard it Denoiser...

Let me get back to you in a while...

EDIT 1: If you did the recording maybe the best way is to just redo it. You recorded it extremely quite, with no gain at all. I'm trying to clean it up, but from what I can see this is the best thing to do. Just hang on another 10 minutes and we'll see...

EDIT 2: Here you go:
http://rapidshare.de/files/6601949/walkingtry.wav.html

That's the best I can do in 5 minutes and under the circumstances.
Hope it's all right!

Kinoko: Just note that it is loud! You will have to put the volume down a lot!

DoorKnobHandle · Sat 22/10/2005 12:29:53

I'd help but when I download your wave file, it's really quiet and I only hear noise, no footsteps at all. Maybe it's because of teh evil 6,66 seconds length?

Oh and this is prpbably not the right place to pust something like this as long as you don't want any comments or critique on it.

TheYak · Sat 22/10/2005 12:49:28

Maybe it's just because my volume was so high but Nikolas' attempt sounded like somebody walking on gravel in a full bathtub.

De-noisers tend to distort the recorded sound. I gave a shot with Audacity, but the more I tried, the worse it got. Now it sounds like a skipping record with a weird high-pitched washiness at the end of each beat.

Geocities link :p

I'd try recording again. It actually sounds like you've got the gain on the mic amplified but the sound isn't that loud. It sounds a lot like transformer-buzz so you're getting feedback or you're recording from atop a power line. If you can't get rid of the noise whilst recording, then record a few seconds of nothing so that only the noise is left. That way that particular sound can be isolated using frequency filters or de-noising mechanisms.

Edit: Here's another shot at clean-up. I messed with low-pass/high-pass filters to remove most of the noise and a de-noiser to attempt to reduce hum. The problem is that the noise shares a lot of the same spectrum with your sound. That, and they're about the same volume (sound's a bit quieter) so it's hard to isolate. Maybe a sound guru like LGM or Geoff can fix it.

Nikolas · Sat 22/10/2005 12:51:39

I know...

I actually didin't use denoiser, but Band pass, a couple of times and EQ...

The best thing is to reredcord it...

EDIT: I will jump in to defend my 5 minute work:
It is normailized that\s why it is so loud. When you bounce or export an audio file, you usuallyu normalize it and leave the others to deal with the volume. if you put it to 20% you won't hear the noise but the futsteps. And it does sound like walking in grass, or something like that.

Kal-El · Sat 22/10/2005 13:19:45

And if you can, record it at a high quality like 44MHz.

Elliott Hird · Sat 22/10/2005 13:31:12

I think you mean Khz. Heh.

Kal-El · Sat 22/10/2005 13:43:14

Get out. Seriously. Get out.

Elliott Hird · Sat 22/10/2005 13:48:22

44Mhz is an impossible thing

Kal-El · Sat 22/10/2005 13:50:24

You obviously haven't seen my Magnum .44MHz.

TheYak · Sat 22/10/2005 13:51:19

Whatcha wanna do is record it at like 1.21 gigawatts.

(wasn't trying to step on your 5-minute job there nick, just was a little blown away by the volume after listening to kinoko's quiet sample. Normalization is the right way to go, but so many system sounds are so much quieter by comparison that any normalized waveform tends to be booming loud)

Nikolas · Sat 22/10/2005 13:54:34

I know, sorry for jumping...

Let's see what Kinoko has to say. After all she might like any of the three different versions we did, and if not she can always REDO!

Thanks mate!

Kal-El · Sat 22/10/2005 13:58:20

As simple as it sounds though doesn't making sure you're recording in a quiet room NOT next to a whirring PC make a difference? The hum could be that as daft as it sounds.

loominous · Sat 22/10/2005 14:22:27

Cool Edit has a pretty good noise reduction feature which analyses parts with pure noise that you select, and then filters out those frequencies only (or something), when applied to the whole file.

The results vary in quality depending on the amount of noise, how much you reduce it, the characteristics of the noise and sound, and how long bits of pure noise the file has that can be analysed.

Since the file is a minor nightmare in these aspects, the result has some artifacts:

The modified file (.5 mb)

It's a really simple four click procedure, but you'd need to get hold of the program (think any version will do).

Kinoko · Sat 22/10/2005 18:45:05

Thank so much everyone! I appreciate your time to help me with this silly problem. I will listen to them all tomorrow now, because for now, it's late and I'm tired and sortof drunk.

EDIT: You guys rock, thanks so much! After much umming and ahhing, I've decided to go with your second one, Yakspit. If you don't mind me using it, that is. I still have to edit it and change it a bit, but if it's okay with you...

TheYak · Sun 23/10/2005 03:23:15

Absolutely. It was more an example than anything but if you're so inclined, go for it.

Even if you can't duplicate the sound you wanted, just recording nothing would help in cleaning it up using Audacity or Cooledit for noise reduction (same method).

hedgefield · Sun 23/10/2005 12:41:10

If you have these kind of problems in the future, I recommend Audacity.

It has a built-in noise removal filter, where you can select a piece of the track that you define as 'noise', and then it searches the track for similar tones and removes them. It usually works pretty well. The equalization and normalization tools are also very useful.

And best of all: it's freeware!

TheYak · Sun 23/10/2005 13:32:32

Useful linkage, though that particular descriptive is getting a bit repetitive at this point.

Snarky · Sun 23/10/2005 15:51:05

I'd be very wary about using noise reduction filters. I once made a short film which I edited on my computer. In order to clean up the sound, I used the noise reduction filters in Audacity and Goldwave. It sounded pretty good on my headphones and computer speakers. Then I entered it into a local competition. When it played over the sound system in the auditorium, the entire sound track was full of weird blips and washy screams, and people's voices sounded like a tape running at uneven speed. My film was totally unwatchable (though to be fair, only in part because of the sound quality), and I was humiliated in a hall full of people. The competition jury made a special point of making fun of me. A learning experience for sure, but not one I recommend to others.

fovmester · Mon 24/10/2005 12:54:28

What you want to do is to buy a good mic, go to a really quiet place, ( like the country side or a university at night) and do your recordings there. That's the way to get the best results. It takes a bit of time and planning, but it could very well be worth it!