-Inf noise floor too low - ACX Help please

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Ani365
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-Inf noise floor too low - ACX Help please

Post by Ani365 » Thu Jan 07, 2021 11:06 pm

Hi,
I am recording my first audiobook and could use some help. I've recorded tons of auditions and done a lot of familiarizing myself with Audacity to prepare myself, but I keep running into this one nasty issue. No matter how consistent my settings and studio setup is, sometimes my recording will pass the ACX check and be within range, and other times the noise floor will be "too low" -inf dB Warning (too low - Dead silence sounds unnatural.)
I don't understand why this is because I can be recording an entire section, then pause for a moment to sip water or whatever, jump back in and only one of the sections will pass. Am I doing something wrong? My studio setup is decent, or as good as it's gonna get at least.

I'm attaching my unedited recording if that helps. You can see, if you delete the first 17 minutes or so, the rest WILL pass the ACX check just fine. The first half doesnt.
I'm putting it through all the steps ACX mastering suggests - low rolloff for speech, loudness normalization and limiter as specified here:
https://wiki.audacityteam.org/wiki/Audiobook_Mastering

However I haven't even done the noise reduction and it doesn't pass. Is there any way to save my recording?
I appreciate the help!
Attachments
No edit.aup
(55.18 KiB) Downloaded 6 times

steve
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Re: -Inf noise floor too low - ACX Help please

Post by steve » Thu Jan 07, 2021 11:10 pm

Ani365 wrote:
Thu Jan 07, 2021 11:06 pm
other times the noise floor will be "too low" -inf dB Warning (too low - Dead silence sounds unnatural.)
That means that there is some "absolute silence" in the audio that you are analyzing. "Absolute silence" meaning "total" silence, no sound at all.

The leading "silence" at the start of the recording, gaps between words, gaps between sentences should not be "absolute silence". They should be normal "room tone".
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kozikowski
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Re: -Inf noise floor too low - ACX Help please

Post by kozikowski » Fri Jan 08, 2021 12:26 am

I'm attaching my unedited recording if that helps.
It would. But that's not what that is. You posted an AUP file which is an Audacity Project Manager file. It's text instructions, not sound. If you want a sound file, you have to export one.

It would be good to post a sample. Use this format.

https://www.kozco.com/tech/audacity/Tes ... _Clip.html

Read down the blue links. They're very short.

Having dead silence in your work does sound a little funny, but that's not the major reason dead silence is a problem. Since nobody can record that in their home studio (or any other studio), it means you "messed with the sound," and ACX doesn't much like that. They have a failure called "overprocessing." They used to carefully and critically analyze a performer's work and give the benefit of the doubt, but that was before the sickness. Now, everybody with respiration and a pulse wants to read for audiobooks. One mistake and it's full stop. Next!

It's possible your pause and resume is causing troubles. We might be able to tell that in your test.

ACX Check looks for a brief quiet period in your performance, measures it, and assumes everything else matches. It might not. If that one quiet piece is the only quiet piece, then your performance is broken and it will probably fail other tests later. ACX Check works in a similar manner to ACX's own hardware test. After you make it through that, you then have to pass Human Quality Control where a real person listens to it to find out if you're theatrically marketable. Nobody is going to pay you to read to them if your voice scares the horses.

A word on recording hygiene. It's an amazingly good idea to export a WAV (Microsoft) 16-bit sound file when you get to the end of a reading—before you start editing, correcting, and filtering. Count the forum posts from people whose computer fell over dead half-way through an edit session, and they had no backup.

ACX wants you to produce your final work (Edit Master) as a WAV first and only then burn the MP3 for submission. If they find something minor wrong you need to fix the WAV and then make a new MP3. You can't edit an MP3 without causing damage.

You would think you should Save an Audacity Project rather than exporting a WAV file. You can do both, but Audacity Projects are more brittle than WAV files and more likely to fail.

Count the forum posts of people whose Project will not open. The new version of Audacity is going to do projects a different way and is less likely to Hindenburg on you.

Koz

Ani365
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Re: -Inf noise floor too low - ACX Help please

Post by Ani365 » Fri Jan 08, 2021 4:45 am

Hi all,
Thanks for the prompt responses. Appreciate it.
The thing is - even before I do any edits at all I'm getting this error (sometimes, but not others). The exact same recording can have a noise floor too low (-200 db) and another section (taken a second earlier or later, with no changes to literally anything) can pass within range. How is that possible? Obviously I've tried doing edits but the problem is persisting before I start mastering at all. I've taken a look per your suggestions and I don't actually see any spots or gaps where there could be dead silence. And if there was - how can I avoid this? This audio is already 35 mins long, and I cant identify the spot giving me this issue. How am I to avoid this once the recording gets to 7 hours?

I don't have access to my studio at the moment to record the sample you're suggesting kozikowski but I will try and do that ASAP. I'm on a bit of a deadline and hoping to do more recording tomorrow.
Please, if you have any more suggestions or thoughts I would really appreciate it. This is really frustrating because it's the kind of error I can't seem to fix just by troubleshooting. I must be missing something here.

Okay Update: Very strange... but I exported the file as a WAV file in order to send to you (file was too large though), and by chance opened it as a new track/file, took a look, and the noise floor passed. made all the other mastering edits listed before (limiter, etc), and it passes. I suppose it's possible I had done some effects to the track before recording, deleted and then rerecorded on the same track, but it didnt seem like the effects "stuck around" so to speak. Sorry if this makes no sense at all, I'm not sure how to describe clearly the situation...
But essentially, why on earth would exporting it as a .wav file solve the problem? Very confused about all this and feeling overwhelmed.
Still though - now that it's mastered and it passes ACX standards, I hear a but of a weird lingering noise in the background. (attached file called - "Edited". It's not the classic humming im used to hearing in my unedited files. Is this from mastering? anything I can do to clean up my audio better aside from making it ACX standards? I'll also attach "no edit" so you can hear it before mastering. Thanks for the help all!!

Thanks for the help.
Attachments
Edited.wav
(965.41 KiB) Downloaded 5 times
No edit.wav
(1.97 MiB) Downloaded 7 times

kozikowski
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Re: -Inf noise floor too low - ACX Help please

Post by kozikowski » Fri Jan 08, 2021 11:04 am

Before we get to 7 hours, lets solve this piece at a time.

It's nearly 100% certain that rumble is one of your fans in the background. I made the first 2 second worse so you can hear it.

No-edit-Noise.wav
(262.96 KiB) Downloaded 6 times

If it's a laptop cooling fan, that could be why it comes and goes as the computer heats up. It could be the room heater coming and going. We should solve that first. You can't do quality recording with that kind of noise in the studio. It's too loud for normal noise reduction.

ACX wants all their chapters to match. You can't have some chapters with tons of noise reduction and corrections and some without.

Also, we note I can hear you moving and gasping. Remember this is the 2 seconds where you're supposed to freeze and hold your breath? I wasn't kidding.

What in your room has fans? The computer is the obvious one. Heater? Air Conditioner? Apartment complex air handler? Noise is the scary measurement. -60dB means your room noises have to be a thousand times quieter than your voice. Or quieter. Nobody's house can do that without some soundproofing help.


You can't post much more than about 20 seconds of mono WAV sound on the forum. I'm kind of surprised that No edit.WAV made it. 2MB is the limit. It's enough for a sample and that's it.

Find the fan. This isn't easy. Do you have a friend who can help you search? Sometimes a friend from outside can be more attuned to room noises you just got use to.

Koz

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Re: -Inf noise floor too low - ACX Help please

Post by steve » Fri Jan 08, 2021 12:54 pm

Ani365 wrote:
Fri Jan 08, 2021 4:45 am
The exact same recording can have a noise floor too low (-200 db) and another section (taken a second earlier or later, with no changes to literally anything) can pass within range. How is that possible?
The ACX Check plug-in looks for the quietest half second in the selection. This is an average measurement ("RMS") over a half second period.

For a microphone recording, with a bit of effort and a very quiet room and reasonable equipment, it should be possible to achieve a recording where the voice is a bit more than 60 dB louder than the "noise floor". In other words, if the peak level is -3 dB, the noise floor for a good, clean recording, would be expected to be around -60 dB or a little lower. If however the noise floor is much lower than that (say -100 dB), then there's something fishy going on because it's almost impossible to achieve such a low noise floor even in a professional recording studio with very expensive equipment.

One possible explanation for "-200 dB" is that there may be a short period (less than half a second) of absolute silence. Remember that the plug-in is measuring an average level, so if the real noise floor is say -60 dB but there is a half second section in which most of the half second is absolute silence, then the average measurement will be considerably below - 60 dB.


I think it would be a good idea to find where these extremely quiet sections occur. You can probably find them with the "Silence Finder" effect (https://manual.audacityteam.org/man/silence_finder.html). Try applying Silence Finder with these settings:


silencefinder.png
silencefinder.png (26.8 KiB) Viewed 236 times
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Ani365
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Re: -Inf noise floor too low - ACX Help please

Post by Ani365 » Fri Jan 08, 2021 4:51 pm

Hi,
Thanks. Steve - I tried the silencer finder and you're right, it worked! There were a couple spots of total silence right at the spots where I'd resumed recording that my own ears couldnt pick up on. I deleted the little sections once the finder pointed them out to me and it worked. Thanks SO much. I will continue using that in the future.

kozikowski - I will make more of an effort to be silent for a few solid seconds before recording - sometimes it's hard for me to get settled since I have to restart a bunch of times usually if my voice doesn't come out the way I want it to. Thanks for the tip.

RE: the fan - that's the thing, I don't think it's my laptop fan since I can't hear it (I used to have an old laptop with a wildly loud laptop fan and thats why I upgraded), though I suppose it's possible it's super quiet and not audible to my ears but is picked up by the mic? No sure what to do if that's the case since I can't even tell it's happening.. My ceiling fan was switched off, and my heat comes through baseboards in my floor so the only noise that usually makes is a random pipe creaking in the middle of the night. I've been looking around trying to determine the source, but I don't actually see anything that could be making that background noise...
If I listen to a clip from the end of my 35 minute recording, that sound doesn't seem to be there or at least not as strongly, so I get why you're thinking there was some noise going on in the beginning... I uploaded a tiny clip of the very end of the 35 minute session - I can actually hear whatever that noise is fading out. but is there any other reason this would happen, like something with the mic, or my equipment/setup?
I really can't see anything aside from my computer capable of making that kind of white noise.
Hearing all this - do you think I should re-record (ugh) or is there a way to salvage this recording? Sounds like record is best, being that ideally I could remove whatever is making that sound moving forward, but again, I'm not even sure what's making it, I didn't hear anything when I was recording.

Thanks again for all of the help, this has already been immensely helpful!
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kozikowski
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Re: -Inf noise floor too low - ACX Help please

Post by kozikowski » Sat Jan 09, 2021 1:36 am

You're right. Starting at 10 seconds, the trash goes away. Boop, gone.

That's not white noise. White noise and pink noise are cousins to spring rain falling on the trees.

ItStartedRaining.wav
(1.17 MiB) Downloaded 7 times

You have straight rumble cause by a fan or a pump

Did you ever tell us what your microphone was? Is it sitting on the table? Maybe it should not be sitting directly on the table. You can get vibration coming up through the floor and table. You may not be able to hear it, but it can get into the show.

Image

Doesn't have to be Stephen King, but it should be a heavy book. A 3/4" thick pile of magazines would work, too. It's almost impossible to get table vibrations through that to the microphone. Make sure the microphone cable is not tight. That can carry noises, too.

Koz

Ani365
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Re: -Inf noise floor too low - ACX Help please

Post by Ani365 » Sun Jan 10, 2021 5:37 pm

Hmm, interesting.
I have a Blue Yeti (not the pro), and I actually have been using this: https://smile.amazon.com/gp/product/B07 ... UTF8&psc=1
Recently purchased to try and dampen any echo, which seems to work.

I wonder if it's possible the laundry was going on the floor below me? I live in a high-low ranch and I normally can't pick up sounds from below me, but possibly? I'm going to do some more recording tomorrow and see if the sounds is still happening, etc. and report back.

Thanks for all the help!

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Re: -Inf noise floor too low - ACX Help please

Post by kozikowski » Sun Jan 10, 2021 6:34 pm

There is a sister forum posting to yours which is another "This is impossible, but it's happening."
to try and dampen any echo
Yes. It will do that. That's an example of the thing I constructed out of furniture moving blankets and plastic pipes which is itself a copy of a different commercial product. Furry Caves. All work famously.

The recording computer is a laptop, right? I think you said that in the messages.

Do you know where the laptop built-in microphone is? Mine just left of the left-hand shift key.

It's not that uncommon to find you're recording from two microphones—oddly enough. Do a scratch test. Start a recording and scratch your Yeti grill and then scratch the laptop microphone.

https://www.kozco.com/tech/audacity/cli ... hTest2.mp3
I wonder if it's possible the laundry was going on the floor below me?
My Kelvinator® with a load of flannel sheets would make exactly that kind of noise.

Koz

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