Noise Removal problem

Special Interest Groups Recording Techniques
1

Hi. I’ve looked thourgh all 407 blogs in the recording section and none appear to address this noise removal problem I am seeing. I’ll do by best to explain it. Please help!!

I have many original recordings on cassette tapes. I have tried both V1.2.6 and 1.3.5beta. OS: Windows XP, PC is only 2 years old Dell. Using Hardware: SoundMax Integrated Digital Audio soundcard.

Problem Example:

I record onto Audacity peak around -3db. noise/hiss is around -36 to -26db depending on recording.

I select a 1-2 second section of noise only, then using noise removal effect teach it the noise. So far so good.

Then I select the whole recording (~2minutes long) or even just a short section. no matter.

I use the noise removal feature. What I get is a digital noise slurry that comes through during the music in the background and it is faint. The non-music areas are perfectly silent which is good. If I adjust the noise removal to its least (Less) position the digital smagma is worse and can be easily heard even in the silent areas. If the noise removal is selected at most (More) it actually changes the tones of the instruments.

I wish I had a better example of this digital noise introduction but I don’t. Audacity 1.3.5beta is able to get rid of the digital background mess introduced but the attack and delay and db settings at best give me a fuzzy woosh sound in and out of the music tones. This recording example is using an old Casio keyboard.

If the recording has pockets of distortion then this my be contributing and possibly the noise removal feature cannot handle peaks of gray distortion?

Any how, any suggestions would be greatly appreciated as I have wasted hours trying to figure this out. my settings are 44K, 32bit float, stereo mix, line in, 128 bit rate, WAV 16bit microsoft pcm, FFt=256 default. Playback and record set to Microsoft Soundmapper and Software Playthrough is checked “on”.

Thank you much!!!

2

Everybody goes into this with the natural assumption that you can rescue any sound presentation from any damage.

You can’t.

Especially if you tried the 1.3 noise tools–which are very good–and they weren’t enough, you’re pretty much dead. Cassette tape noise is wide and flat–hiss with a broad characteristic. If you listen carefully to a single cymbal or hi-hat crash, the trailing edge of that sound is pink noise–wide and flat hiss. I wouldn’t be shocked to find the software passing the attack sound with the drumstick, but clipping or damaging the tail.

Hiss is pretty rough and until a short time ago, was impossible. So any benefit you derived so far may be the ball game.

Koz

3

Hi

Can anyone help me with a problem I am having. I am using audacity for Voice Overs and am having trouble with interference on my recordings, I have used noise removal but have discovered that sound is being recorded when my mic isn’t plugged in! Where is this coming from and how can I rid the recording of this?

Thanks


Liz

4

X-File,

That is an awful lot of noise, you’ll be hard pressed to find a good way to get your recordings sounding decent, let alone good. You’re right that 1.3.5 is the current best that Audacity can do. In case you haven’t seen it, here’s the wiki page on Noise Removal, it might clear up some things, but it sounds like you’re doing it right already:
http://audacityteam.org/wiki/index.php?title=Noise_Removal

Liz,

Without knowing more about your setup it’s difficult to help. My best guess right now is that you don’t have the right input set in Audacity. Go to the edit → preferences → audio i/o menu and make sure Line In or Mic In (depends on how things are plugged in) is selected as the recording source. If that doesn’t help, tell us how you’ve got everything plugged together, what equipment you’re using, and what your recording environment is like and we can work this out. If you’re doing voice over work, it’s always best to get a clean recording to begin with, rather than rely on Noise Removal to fix problems later on.

5

<<>>

Liz. I know it seems like you have the same problem as the first poster, but you don’t really. It’s always good to start a new question thread (it’s too late now) instead of piggy packing on somebody else’s question. Anybody scanning the forum for questions about noise are going to miss any help we’re able to give you.

Next time.

<<<sound is being recorded when my mic isn’t plugged in!>>>

If you’re plugging your microphone into the Mic-In of a PC, you may have a bad or ratty sound card. They’re not the most expensive thing in the world and they easily break. Let’s see what you say.

Koz

6

Hi

Sorry for piggy backing someone else’s question - my apologies to them too. I have never used anything like this before and I didn’t know how to use it - I think see how now, and hope, as you said “next time” that it is ok for me to continue here.

I found the audio i/o menu myself and noticed that the line in wasn’t on my mic, I changed this but it has made no difference. My set up is windows xp, microphone samson co1U. Changing the volume on my pc doesn’t seem to make any difference. Any further info please ask what’s needed.

Because I received a report of some interference on a demo - I can’t hear it on playback once I have recorded my voice - I tested it by recording without voice (just clicking record), normalizing it and then could see/hear the noise on the recording. I am aware that there is some noise from my pc itself which I can block out but can’t understand why the noise is still there when the mic isn’t plugged in. As suggested I will look at the sound card but any other ideas?

Appreciate your help


Liz

7

So you’re recording from a USB mic, correct? Once you have that set as Audacity’s recording source, it should work alright. If Audacity’s recording source is set as something else, you might still pick up the mic, but you can also pick up other sounds that you won’t want (if it’s set to Stereo Mix or something similar).

Don’t bother checking the sound card, if you’re using a USB mic it doesn’t get used for recording.

I can’t explain why you’re getting noise when you unplug your mic. In my experience, Audacity will throw up a warning if you attempt to record with a USB mic that has been unplugged (since Audacity can’t find it anymore).

Are you sure the “interference” that someone mentioned wasn’t simply background noise being picked up because the Mic is too sensitive? If that’s the case, then it’s a problem with your recording environment, not your recording equipment. Condenser Mics like the C01U are very sensitive.

8

Hi

Thanks for you further info. The mic is plugged in via USB - I can however unplug the mic and audacity records a background noise from somewhere (no warning reference no mic appears). I haven’t tried voice recording without the mic plugged in - assuming that wouldn’t work. I was just trying to establish what/where the noise is coming from. The audio in was set as “microsoft sound mapper” which I have changed to samson co1u. The software that came with the mic is “sonar le” which I believe is recording equipment - this is still loaded on my pc - does this make a difference?

After reading the mic handbook I noted that you can either use the mic via USB or with software (SoftPre) - I tried to download this software and it displayed a warning from Windows so I ceased to download. It did, however, still seem to download it. I tried using some of the additional functions on that along with the handbook but couldn’t really make any sense of it and thus deleted the software.

Background noise in my recording environment is my pc which I have blocked out a lot of. Unfortunately once I have voice recorded and normalised I can’t hear the background noise but if I just leave on record without voice record and normalise I can then hear a very loud hissing, crackling noise.

Thanks - any help is very much appreciated as it is driving me crazy!!

Liz

9

I have a theory.

The mic is plugged in via USB - I can however unplug the mic and audacity records a background noise from somewhere (no warning reference no mic appears). I haven’t tried voice recording without the mic plugged in - assuming that wouldn’t work. I was just trying to establish what/where the noise is coming from. The audio in was set as “microsoft sound mapper” which I have changed to samson co1u.

Ok, that’s how you want Audacity to be set up. But before you had the Microsoft Sound Mapper input selected. The Microsoft Sound Mapper is controlled through a piece of software in your OS. You can go to the Control Panel and change the audio settings for the Microsoft Sound Mapper input there (though from my experience it never actually calls itself the MS Sound Mapper, so it’s very confusing).

Here’s my theory: You probably have the MS Sound Mapper set up to record from all the possible sources at once. Since each source is going to add a bit of noise to the signal, it might be adding up to be a whole lot. So when you originally recorded, you were taking in a nice mic signal and then adding a bunch of useless noise on top of it. When you unplug the mic and continue recording, Audacity is resetting itself back to the MS Sound Mapper, so it’s recording all those noisy sources again. If you have a microphone built into your computer then that would explain the bulk of the noise (sometimes monitors have them built in, and many laptops do as well).

Note that every time you plug/unplug that mic Audacity will probably revert back to the MS Sound Mapper, so if you can conveniently leave it plugged in, go ahead and do that. Hopefully setting Audacity to use the C01U directly will solve most of your noise problems. It seems that you’re having trouble hearing the noise that is bothering this other person, how are you listening to your own recordings?

The software that came with the mic is “sonar le” which I believe is recording equipment - this is still loaded on my pc - does this make a difference?

Don’t worry about that other software. If you aren’t using it, go ahead and uninstall it.

Regarding the SoftPre software, I used to own that same Mic. From what I remember, SoftPre isn’t necessary, it only gives you nicer control over the input volume and allows the mic to record even louder than the standard Windows drivers. If the volume is adjusted well already you don’t need SoftPre.

Background noise in my recording environment is my pc which I have blocked out a lot of.

Hopefully this is true, but it can be tricky to do this well. It can also be difficult to hear the noise on your own recordings if you’re listening back over less-than-stellar speakers since you’ve got the original noise source to listen to as well as the noise on the recording. It’s best to listen back with headphones if you’re trying to hear the noise.

Unfortunately once I have voice recorded and normalised I can’t hear the background noise but if I just leave on record without voice record and normalise I can then hear a very loud hissing, crackling noise.

This makes perfect sense. Normalize will adjust an entire signal to peak at a certain value (in Audacity’s case, -3dB by default). So if you record voice + noise, it won’t amplify very much at all and the noise will not be prominent. But if you only record the noise it will really crank it so the noise is very, very loud.

Recording only the noise is useful for identifying the source of the noise, but once you normalize it, it’s useless as a measure of just how loud the noise is.