Hope this is the right section.
Turns out I have pretty low room tone, requiring very little noise reduction EXCEPT for this ugly pink stretch at the bottom. I can use a high pass filter to soften it up a bit without dropping my room tone to near dead silence, but I’d rather get rid of it mechanically. Would a couple of bass traps help you think? Narration for ACX
https://www.dropbox.com/s/8iylqld1pvv20rt/room%20tone.wav?dl=0
Windows 10
5570k cpu
16GB ram
Scarlett Solo 2
AT2020 mic
That’s too big for download and it doesn’t look like it has any silent parts in it.
Drag-select ten seconds of the performance. Make sure you have some silence included. Constant music or show doesn’t do us any good.
File > Export > Export Selected > WAV Microsoft.
Scroll down from a forum window > Attachments > Add Files.
Koz
Oops. I did export instead of export selection. No wonder it was so large. I do that all the time. This is the raw recording. No noise removal or filtering.
Oops. I did export instead of export selection.
I’ve never made that mistake…
I mastered the clip for audiobooks and applied very gentle noise reduction.
As a fuzzy rule, if you can pass that, you can announce for anybody.
This is the abbreviated process for Audiobook Mastering. That first tool is a rumble or low-rolloff filter. That’s gets rid of that red fringe at the bottom of your display. You pass without doing any more than that, but it’s close.
And this was the Noise Reduction I used. Noise Reduction of the Beast. Very gentle. Nobody can tell you’re doing it.
Koz
Interesting on the noise reduction. I’ll give that setting a try. Pretty much doing everything exactly as you showed. I hadn’t noticed how much the roll off reduced the rumble. I was hoping to find a way to prevent so much low rumble, but this will work. Thanks.
This is all the stuff at super low pitch. We have earthquakes that look like that. You can’t hear it, but it can mess up volume and loudness tools. Everything to the left of 100Hz goes away if you apply Effect > Filter Curve > Low Rolloff.
By the time you get to tones like that, that’s not your neighbor with the annoying sewing machine. Your microphone is probably making that.
Here’s the marketing. Low pitched tones like that are expensive to fix, so let’s not. Who’s going to know? Nobody can hear that and you can announce for production and podcasts for years without find it. It’s only if you encounter the need to hit noise and loudness exactly right that the jig is up.
Try this. Wrap the microphone many times in heavy blankets, but leave it running with the cable loosely sticking out. I bet those lumps don’t go away. That’s Analyze > Plot Spectrum. Volume up the left, pitch or frequency left to right. There is no time.
If you do the wrap and it does go away, then you have some impressive rumble somewhere in your house.
Do you get ripples in your coffee cup or wine glass? That’s a Hollywood thing. You can’t photograph an earthquake so you have to have a wine glass in the shot somewhere so they can photograph the ripples.
Koz
A word on using Analyze > Plot Spectrum. It has the annoying habit of changing loudness references on the left to be most helpful to you, in its opinion. The numbers on the left move. It would be as if your speedometer needle stays in one place and the car moves the numbers in a circle.
Anyway, see at around 100Hz, there is a tiny purple spike that goes up to about -78dB? If you run Low Rolloff and then analyze again, the spike will still be at about -78dB. But -78dB is now at the top of the chart.
If you’re not paying attention…
Oh, by the way, yes the ACX audiobook noise limit is -60dB, but as a practical matter, you have to actually hit -65dB or quieter to safely submit. Your work without the Noise Reduction comes in about -63dB or so. Yeah, technically it does pass… But…
https://forum.audacityteam.org/t/audiobook-mastering-version-4/45908/68
Koz
I’m pretty sure my other mic, ES-58, captured a similar room noise. I’ll double check. If that’s the case, it’s probably in the amp or PC or cables.
ACX has a couple of new requirements for readers as of The Sickness. I have to be able to buy your book on Amazon. As near as I can tell, no option. A forum poster tried to publish in both paper and audiobook at the same time. It didn’t go well.
Also, They updated the types of work they will accept. No more cookbooks. Scroll down.
https://www.acx.com/help/200878270
Koz
my other mic, ES-58, captured a similar room noise.
You can see the question marks floating over our heads. This is not “normal” noise. There’s a tone at 16Hz, one equal loudness at 23Hz and then a quieter one at 31Hz. Most unusual. It’s not wall power or normal fan noises. Do you live over a factory? I think you can get computer-controlled milling machines to do something like that.
It could be the Solo. Anything that touches the analog system is suspect. Do the blanket trick. If you can prove it’s not the microphone by substitution and the blanket doesn’t affect it, then nearly the only thing left is the Solo.
If the blanket does make the trash reduce in volume, then you can use the ES-58 on a treasure hunt. The ES-58 is highly directional and you might be able to point to the walls, floor, and ceiling and see what’s louder. I found a bad bass cabinet that way. It didn’t go off when I turned it off.
There’s more exotic possibilities, too. You can have USB System Defects. The computer is supposed to deliver clean, pure, stable five volts up the USB cable to the Solo which then uses it to amplify the microphone, run the lights, drive the headphones, etc. If it’s “dirty” or damaged, the damage may appear in your show.
That’s not likely with a Solo, but the USB microphone people have this problem all the time.
Post back when you have other info. Can you change computers, or move this one to a new location? Doesn’t have to be perfect, just different.
I’m not kidding about moving into an industrial zone by accident. I got called in to resolve a strange sound issue. Turns out they were trying to shoot sound in the shadow of those towers.
Step one. Move to a new studio.
Koz
but I’d rather get rid of it mechanically. Would a couple of bass traps help you think?
Digital filtering is free! 
And, it’s very common to filter-out the deep bass from everything except kick drum and bass guitar in musical recordings, and the subsonic frequencies would still be filtered-out.
A shock mount for your microphone might help and it’s inexpensive.
Bass traps might help but they aren’t supposed to completely kill the bass. They are supposed to kill the reflected bass to reduce/eliminate resonance.
“Soundproofing” means double-heavy walls, etc., and low frequencies are the toughest.
20Hz is considered to be the low limit of human hearing. So some of your interference will never be audible except to cats and dogs—but it still takes up room. I’m not joshing, this is in the range of thunderstorms and earthquakes. Normal houses, apartments, and flats just don’t make noises like that.
How far away from freeways/expressways/highways are you?
Koz
And as a completely side issue, if it is sound, constant exposure to it isn’t healthy.
Koz
There’s a highway barely a 100 yards away, but the traffic isn’t constant. I’ll try taking measurements at different times of the day and night, but I don’t think there will be a difference. If that’s the case, then it’s something in my house or hardware. I plugged in the ES-58 and get the exact same rumble. I’m leaning toward a hardware issue. Swapped out mic cables with no change. Going to try usb cable from solo to pc. Might plug the solo into my other pc and see if there’s any difference.
I plugged in the ES-58 and get the exact same rumble.
Try.
The.
Blanket.
Koz
that too
wrapped a fleece blanket around it until it looked like a giant Q-tip. Eliminated the room noise above around 140hz (the pink bar) but did nothing for the lower.
that too
Excellent. We’re following along in our hymnals and nothing rings alarm bell faster (to mix metaphors) than skipping steps because “It can’t possibly be that.”
My vote is something wrong with the Solo. If you move the Solo to a different machine and the noise is still there, then that’s the only thing left.
Koz
If it is the Solo, then it’s a good chance it’s broken. Microphone interfaces such as the Behringer UM2 and the Scarlett Solo can, on request, provide 48 volt phantom power to those microphones that need it.
That means there has to be a power converter in there because everything has to work from USB five volts.
The converters have to work very well. I’ve never seen interface noise problems like this.
And speaking of phantom power, the AT2020 needs it but the ES-58 doesn’t. Have you been switching back and forth?
I’m on the edge of my seat.
Koz
Hold onto your butts! Unplugged the mic and I still get the low freq noise! Also plugged into different pc with different usb cable. No change.