Noise From Cheap USB Mics

[emmpet8]

I know a lot of members aren't keen on Noise Reduction but I recently got asked for a N.R. version of a file, so I did a quick one, but it wasn't that good. Gekko amusingly described listening to N.R. files as; "the participants are recorded in the middle of an extra-terrestrial abduction" and I can't help but agree.

When I created the N.R. file in question, I selected a blank looking part of the file and did "Capture Noise Point' in Audition, but that probably captured a lot of the ambient sound and then removed it as well as mic noise. USBs are quite cheap, so the mics in them must be very cheap.

With this in mind I decided to see what N.R. would be like with just mic noise as the ‘Capture Noise Point’ source. To achieve this I set a USB recording and then covered it in lots of padding, so it would not be picking up any external sounds. When I listened to the results it was a revelation how much noise the USB itself generated.

I then captured and saved it in Audition, before using it for N.R. on a clip recorded using the USB. I was pleasantly surprised at the result, as in my opinion it was better, leaving the original clip sounding more natural. I’m not saying the extra-terrestrials had left, but it seemed more of a friendly chat than an abduction

It was only a quick test, but if I’m lucky enough to get another result and asked for N.R. again, it’s something I’ll try.

[sndprv]

When I was trying to record Couple 3 from my new batch of sounds, I initially left the USB
hidden behind one of those corridor doors that are held open magnetically (by an electromagnet).
(In the event of a fire, these doors are supposed to close automatically.)
It was a good job that I changed my mind and decided to use the much better handheld Sony
recorder once the session started, because when I got home and listened to the USB recording,
all I could hear was this RRRRRRRRRRRRRRRRRRRR.

[reggind]

Using just the mic and pre amp self noise should work, but finding a quiet passage in the audio should work even better. Actually when I try and clean up a file I do things in this order. I will explain as I go why I do it this way..

First, I use the hi pass filter set to 250Hz and the steepest cutoff slope (I think it is 48 db/octave) that it can do. The high pass cuts all the bass out. This includes lots of rumble and low frequency ambient noise. Also if there is any AC hum this will go a long way in taming that. In the US AC hum is 60Hz, in the UK and some other places it is 50Hz. The 250Hz cut off frequency I pick is just over 4X the US power line frequency and 5X the UK power line frequency so it is very effective at cleaning that up. So now we have our source file sans any low frequency noise.

On occasion I will do a low pass filter pass with the center frequency set at about 12Khz and the same 48 db/octave. This gets rid of any real high frequency hiss. It will also make the file sound "duller" so I don't do this all the time, but if there is a lot of noise, I will do this. My ears are old and I don't hear a lot over 12K anymore. Set it higher or lower or skip it. This and the hi pass part are all about cleaning up the file as much as you can before the noise reduction step.

Next I will do the noise reduction pass. I listen to the file for any gaps and note where they are. The waveform display is helpful but you can not go by it alone. One trick I have found to help me get just a good noise clip is once I have identified a place that has a good clip in it, hi lite it and play it and verify you have all of the "good" part of the clip. Don't freak if you have a bit of content before the "good" part and after the good part. As long as the bulk of it is the good part. Now go into the top menu and under view, click on zoom and click on zoom to selection. Now the waveform picture is just that little selection. Now try and pick out just the good part. It should be a lot easier. Remember once you have it tagged you can hit play and hear what you have. It may take a few tries..

For the noise reduction, load that as the noise profile and I use the following settings. 24 for the sensitivity, 48 for the number of frequency smoothing bands and between 9 and 18db for the amount of noise reduction. The better the clean up job before the noise reduction the more NR you can use before it starts sounding bad.

Oh, at the beginning, if there are any extraneous loud sounds, snip them out. Mic drops , and mic pickups and re drops etc. Start with the most consistent file you can...

The last thing you probably want to do is an amplify pass. This will bring the levels back up. If you wanna save the file, this is the time to do it.

For listening, I normally use the "bass and treble" effect. I will play with booting the volume and the treble to get the desired effect. Little gasps and things said under the breath will start to come out. I listen with the cursor on the skip backwards button and often times do skip backwards as soon as I hear something interesting.

Sex often times has a rhythm to it and often times you get so you kind of expect when the next little gasp or breath is going to be.

Have fun and play with the knobs and sliders. The above should get you on the right path...

Oh one advanced thing you can play with too. Running the NR twice. Once with just the mic and preamp noise and once with the real noise sample. Worst it will do is not work well and you can ctrl Z to undo it. Not that have ever done that (smile)

[emmpet8]

Using just the mic and pre amp self noise should work, but finding a quiet passage in the audio should work even better. Actually when I try and clean up a file I do things in this order. I will explain as I go why I do it this way..

First, I use the hi pass filter set to 250Hz and the steepest cutoff slope (I think it is 48 db/octave) that it can do. The high pass cuts all the bass out. This includes lots of rumble and low frequency ambient noise. Also if there is any AC hum this will go a long way in taming that. In the US AC hum is 60Hz, in the UK and some other places it is 50Hz. The 250Hz cut off frequency I pick is just over 4X the US power line frequency and 5X the UK power line frequency so it is very effective at cleaning that up. So now we have our source file sans any low frequency noise.

On occasion I will do a low pass filter pass with the center frequency set at about 12Khz and the same 48 db/octave. This gets rid of any real high frequency hiss. It will also make the file sound "duller" so I don't do this all the time, but if there is a lot of noise, I will do this. My ears are old and I don't hear a lot over 12K anymore. Set it higher or lower or skip it. This and the hi pass part are all about cleaning up the file as much as you can before the noise reduction step.

Next I will do the noise reduction pass. I listen to the file for any gaps and note where they are. The waveform display is helpful but you can not go by it alone. One trick I have found to help me get just a good noise clip is once I have identified a place that has a good clip in it, hi lite it and play it and verify you have all of the "good" part of the clip. Don't freak if you have a bit of content before the "good" part and after the good part. As long as the bulk of it is the good part. Now go into the top menu and under view, click on zoom and click on zoom to selection. Now the waveform picture is just that little selection. Now try and pick out just the good part. It should be a lot easier. Remember once you have it tagged you can hit play and hear what you have. It may take a few tries..

For the noise reduction, load that as the noise profile and I use the following settings. 24 for the sensitivity, 48 for the number of frequency smoothing bands and between 9 and 18db for the amount of noise reduction. The better the clean up job before the noise reduction the more NR you can use before it starts sounding bad.

Oh, at the beginning, if there are any extraneous loud sounds, snip them out. Mic drops , and mic pickups and re drops etc. Start with the most consistent file you can...

The last thing you probably want to do is an amplify pass. This will bring the levels back up. If you wanna save the file, this is the time to do it.

For listening, I normally use the "bass and treble" effect. I will play with booting the volume and the treble to get the desired effect. Little gasps and things said under the breath will start to come out. I listen with the cursor on the skip backwards button and often times do skip backwards as soon as I hear something interesting.

Sex often times has a rhythm to it and often times you get so you kind of expect when the next little gasp or breath is going to be.

Have fun and play with the knobs and sliders. The above should get you on the right path...

Oh one advanced thing you can play with too. Running the NR twice. Once with just the mic and preamp noise and once with the real noise sample. Worst it will do is not work well and you can ctrl Z to undo it. Not that have ever done that (smile)

Thanks very much for the very comprehensive reply and great suggestions. In general I'm with the 'as it comes' brigade and there's also the factor of time. Having looked through 10 plus hours of a recording, I've already spent a good deal of time, so if I'm busy with other things, I don't bother doing anything to any finds. I guess you could call it being lazy

You would probably be horrified at my N.R. as I'm fairly drastic there. Again, you could call it being lazy. I do work on a copy of the original, so I'm not taking risks. I work in Spectral Display and first I select any frequency below 200 Hz and press delete. It's then any frequency above 5 K and press delete. After that I'll try the N.R.

I do admit that if the capture is a bit special I do things a bit different. There I'll look at the sounds that matter (sighs, gasps, moans etc) in Spectral Display and carefully note the highest and lowest frequencies they occur at. I'll then use something like 30 Hz below the lowest and 0.5 K above the highest as the frequency levels to delete at the top and bottom of the range. Still not much finesse I know, but it tends to work reasonably.

Thanks again for the suggestions and I will bear them in mind if I do any N.R. that matters to me. I'll also try running N.R.twice as suggested, when I do it.

[reggind]

I usually start off with the raw file. If I find easy to clean up stuff in the first minute or two, I will do that, than if it seems there is action going on under the noise, I will try and clean that up. I start off lazy and work my way up.

[Bcgolfer]

Thank you for the instructions. Very clear

[Bcgolfer]

Thank you for the instructions. Very clear