Noisy neighborhood...

[Allan M.]

I've been trying my hand at recording for a while now, redoing my own stories over and over, trying to get the hang of the technical details. I have a Aspireone Netbook and an M-Audio Producer mike.

While its usually rather hard to notice, after running the audio through the Levelator, I've noticed that road noise is much more evident. I have a reasonably dead space to work in, but nothing I've seen can dampen the deep rumbles of passing Harley humpers and diesel trucks. Considering I live on the corner of a main connector to the local highway, I can't do much about stopping the noise.

I'm just trying to get my voice out there, and learning how to use the equipment. Considering this is the Mentoring section, I suppose this is the best place to start.

[Veronica Giguere]

Wow, I sympathize. My neighbors' lawn service has this uncanny ability to show up right as I get set up to record an episode. Makes me want to swing a mic at somebody... but I love my equipment too much.

Folks will probably suggest moving to a closet or similarly dead/dampened space. You may have to go a step further and record at "odd" times (least likelihood of traffic, etc.) to really cut down on the noise. Having the Netbook gives you a degree of mobility that those of use who use desktops to record don't have; could you 'borrow' quieter space from a friend? If there's a local community college or university, you might be able to speak with the Humanities/English/Communications/what-have-you department about borrowing classroom space, or your local library might be willing to help out a budding author.

[Allan M.]

I do have a sort of booth built, though I call it my hobo shack. It was made from an old twin mattress and a damaged futon, with this and that to support and pad the other walls. Its actually pretty decent at keeping down the internal noise, but almost useless at the outside noises. They'll rattle the whole house! My windows sometimes start vibrating in harmony with the noise. I wonder if that spot down by the railroad tracks would be quieter...hmm...

Lawnmowers are a frequent occurrence around here too. Them and the jingle-bells of the local ice cream pushcarts. With regular voice acting, a distinct noise is easier to re-record, IMO, compared to being in the middle of a dense paragraph and suddenly someone drives by in their monster pickup.

My wife and I have taken to driving into the country and recording in the car, but it has its disadvantages. It does make it harder to get motivated. Its not just 'walk in to the old closet and work for a while.' And this road never seems to stop, though it does cut back. I was up at 3am the other day, and thought I could do some recording. Nope, the trucks with the engine-break noise are actually worse at night.

[Nathan Lowell]

A couple of things.

Turn the gain down and try to record just your voice. The M-Audio is a USB condenser mic and those are notoriously sensitive. You can probably record at near flatline levels and boost your output in post-production.

I have this problem with airplanes and heavy trucks, too, and my takes are frequently laced with long pauses while I wait for something to pass. That's gonna be more difficult when the noise is non-stop, but if you can drop the gain enough that the normal levels of noise don't get recorded, then waiting for the few loudest ones *should* work.

Good luck with it ... this is one of the most aggravating problems to try to beat.

[Curtis Carlsen]

If the noise only becomes really audible after you run the audio through levelator, then I would guess that the normalizer in levelator is jacking the gain way up when you are not talking. And that you mainly are hearing the road noise when you are not speaking or speaking very softly. One thing you could try is running your audio through a noise gate before you run levelator on it. The noise gate, also called an expander, will cut out any sound below a certain volume level. So you set a trigger point on the audio that is quieter than your voice but louder than the traffic noises. It won't cut the noise out if it occurs when you are speaking, but from the symptoms you describe, I'm guessing you aren't hearing the noise when you speak, only in the quiet parts. If you are using Audacity, you can download an expander plugin that would do the job fine. It may not solve the entire problem, but I'll bet it improves it a lot.

There is an expander for audacity on Windows at: http://www.gaclrecords.org.uk/audacity.html called Dr.Expander, that you could try. I haven't actually used this one in a long time, so can't give detailed instructions. If you don't like it, there are a couple others as well if I remember correctly.

You need to set the threshold, and attack/decay times. Good attack and decay numbers are usually 50 to 200 mSeconds and the threshold will depend on your room/microphone quality. Good luck.

If your mic has a switch to reduce the mic gain (usually labelled "-10dB" or some such, you could try that. Also, if it has a bass boost, be sure to turn that off, since it would amplify the low frequency rumbles.

[Curtis Carlsen]

Hmmm, another thought. Mattresses should be cutting down the noise pretty well. You say the whole house shakes; do you have wooden floors? I've seen wooden floors carry noise. You could try putting blankets on the floor of the hobo shack. Also be sure that you have something isolating the microphone from the floor. A metal mic stand or a piece of wooden furniture will transmit the low frequency sound right into the microphone through it's handle. Blankets or foam would probably improve things. When in doubt, add blankets. Most microphones companies also make isolators that screw into the mic stand, and isolate the microphone from the vibrations.

[Allan M.]

The main house has hardwood floors (the living room is an echo chamber) but my booth sits on concrete. I'll try padding the desk and mic stand.

[Dan Sawyer]

Ah! One of the reasons I don't like Levelator.

Heavy trucks and Harleys both have heavy bass curves that all but the lowest human voices don't share. Run an EQ pass on your audio before handing it to levelator, cutting out ALL frequencies below 125khz (or, if you're a tenor, below 250khz). This is called a low-cut filter, and will help your problem considerably (though it may not completely solve it, depending on the harmonics of the room).

On the subject of Noise Gates -- a lot of people assume they work like rolloff, where it desensitizes the quieter sounds and gets rid of background noise while leaving your voice intact. This is very much NOT the case. They're intended to squelch extra tone with overdriven guitar amps -- don't use them with unaugmented human voices. They operate like a physical gate -- when you have noise above your set threshhold, the gate opens all the way, which means all the noise that you were just cutting out comes back in. This will be profoundly irritating for your listeners - the human ear can tune out a constant noise floor, but it WILL notice a zero noise floor jumping up to -40db every time someone speaks.

Expanders are a bit more of a complex subject, but I'm gonna guess that if you're running through levelator then you're trying to compress the dynamic range of your signal and average out the loudness -- this is the exact opposite of what an expander does, which is to maximize the dynamic range in your signal. Although this can sometimes drop your noise floor, it's not a cure-all, and if you're not careful you're likely to wind up doing a lot of audio processing for what basically amounts to summing to zero.

Sorry to be a party pooper, but, like I said at the beginning, try the EQ low cut. If what you describe is reasonably accurate, it should help.
-Dan Sawyer

[Curtis Carlsen]

This is mostly true. I have however found that as long as the noise is low relative to the voice there is no issue. This comment seems to be referring to constant background noise. If the traffic noise is intermittent, which is what I was thinking of, then this can be an issue. However, -40 dB noise is rather high. If your noise is at 40 dB relative to to your voice, you probably have a problem too severe for the noise gate. However, I have had very good results with marginal equipment.

I am not an audio professional, and my advice may not give professional quality audio. But I think most folks here are trying to get decent audio with low-end equipment. I find the noise gate a good tool in that arena. I've had far better luck with it than with sampled noise removal algorithms.

[Allan M.]

I've noticed that effect when attempting to get a good result from the Audacity Noise Removal tool, it seems to work as something of an adaptive noise gate. It is easier for me to listen to the constant noise level than the results after the filter.

I noticed the same effect in the Levelator. I liked the way it made the recording fairly uniform in volume, but the noise underlying the recording made it hard to listen.

I did get a little better result after the recommended EQ low cut. I also found that my vocal sound comes out better when I keep the mic above my mouth, instead of below. I don't have a terribly low speaking voice, but it does make a difference.

[Curtis Carlsen]

My understanding of the audacity tools is that it is doing some kind of adaptive filtering. Nothing like the expander. The expander algorithm is simpler.

I've had bad luck with the audacity noise removal. It caused a high frequency distortion/whine in the sample I tried it on. Very annoying. I have had much better luck with the expander/noise gate (the term noise gate is an older term for the expander).

[Allan M.]

I did a short sample, with my equipment in its usual arrangement and the gain set at about half-maximum. If I go lower, it is hard to boost the level in post without lots of noise. Higher and I tend to clip. There's a tricky part about this mic, though. Every time it gets plugged in, it defaults to its minimum gain level, though the slider shows the last selected setting. I have to manually go in and move the slider, then move it back, every time.

I didn't actually notice any truck noise in this clip. The EQ low cut did help with the one I noticed before.

Maybe I'm being a perfectionist, but I would like to squelch that hum in the background if possible. It isn't the computer fan, as the fan was not on. There are no other electronics, cell phones, or fluorescent lights within ten to fifteen feet. Any suggestions? I'm hoping to get a reasonably CD quality sound, if possible.

I realize the writing isn't very good. This was actually an excerpt from my draft, since it was on hand.

[Curtis Carlsen]

If this is a USB mic, then I'm a little surprised you're getting that much hum. Perhaps your computer is exceptionally noisy, and the noise is coupling to the microphone over the USB cable. Do you have a different PC you could use as a test.

Is there any kind of volume adjust on the microphone itself? sometimes if gain settings in the first stage is too low, you get excess noise in the end result. If I have a mixer or microphone with a gain adjust on it, I set that first, going as high as I can without clipping or distortion, then backing that one off slightly , and then I set the volume gain in the software to give me the final level I want.