Hi. I’ve been reading about how to master a recording to pass ACX check. Attached is a completely unfiltered audio clip, per instructions. When I go through the list of adjustments: filter curve, loudness normalization, and limiter, I can usually pass peak level and RMS level, but noise floor too high. I simply don’t know how to adjust this within noise reduction. I can’t come up with a set of numbers that don’t make the RMS too low…
My home system is using Focusrite Scarlett Solo 3rd gen (very difficult to come up w audio that’s not too quiet; gain almost at max), Marantz 1000 cardiod mic w pop filter, and Windows 10, newest version of Audacity.
Any help would be greatly appreciated. I’ve been stalled for weeks on this.
I like the voice. You sound exactly a favorite aunt telling us a story. Perfect story-telling voice.
I can force it to work. This is the mastered track and the analysis.
I think there’s something in your studio buzzing or humming, plus I think I hear your computer fan (or air conditioning) noises. So it’s two problems which would drive you nuts.
I surgically removed the tone and then applied gentle noise reduction. You got lucky because all these shenanigans affect different tones than your voice. That gets you down to the posted background noise or Room Tone. Passes easily.
You can go with that, read successfully, make a fortune, and move to the California coast, or we can try to find out what’s doing it. The down side of the surgical approach is you can’t change anything while you read a book. Book chapters and segments have to match each other. There is no “today I think I’ll use this microphone.” ACX doesn’t like that very much.
Are you reading from a tablet? That seems to be popular. Can you print “Catskill Cows?”
Read from the paper. Bring a candle or flashlight with you. Turn off all the lights and put the tablet in the garage. Start a recording just like you did. I expect that one low-pitch tone to vanish and we can go from there.
Koz
(I can’t listen to your file right now 'cause I’m at work.)
I can usually pass peak level and RMS level
If you follow the recommendations, those will pass every time.
I can usually pass peak level and RMS level
Most people recording at home fail noise (before noise reduction).
I can’t come up with a set of numbers that don’t make the RMS too low…
Noise reduction shouldn’t affect the RMS or peak levels.
(very difficult to come up w audio that’s not too quiet; gain almost at max),
Digital levels aren’t critical but good-strong acoustic & analog levels are important. A good signal-to-noise ratio means you don’t need as much amplification, which means your noise doesn’t get amplified as much. You should be fairly-close to the mic, speaking with a strong-confident voice (without straining or shouting).
I believe that’s a side-address directional mic, so you should be speaking into the front side… Not the end or back-side.
And of course, your “studio” should be as quiet as possible. Sometimes that means turning-off the heating/air conditioning or moving the computer outside of the room so you don’t pick-up the fan noise. I’ve even read about someone unplugging their refrigerator. Sometimes you might have to record late at night or whenever it’s the most quiet. You still probably won’t pass but you can get-away with less-aggressive noise reduction.
The preamp in your interface will also generate some (electrical) noise, and sometimes electrical noise gets into the preamp through the USB power supply. But, the acoustic room noise is usually the biggest issue. Again, a stronger analog/acoustic signal gives you a better signal-to-noise ratio.
P.S.
If you are not submitting to ACX you can ignore the -3dB peak requirement and limit to 0dB (or near 0dB like -1dB or -0.5 dB). 0dB is the “digital maximum” for many audio formats and for analog-to-digital (recording) and digital-to-analog (playback) converters.
MP3 compression changes the wave shape and some peaks end-up higher and others lower, so if you normalize to 0dB the final MP3 can end-up with peaks over 0dB so some people normalize to -1dB if they are making an MP3.
Hi Koz -
I am super impressed that you were able to fix everything! Now I just need to know exactly how you did it, and, if you are willing, please explain it as you might to a 10-year-old. 
I did not have a tablet in the closet with me; just my laptop, right next to the mic, actually. And I don’t think I had the closet door shut.
“I surgically removed the tone and then applied gentle noise reduction. You got lucky because all these shenanigans affect different tones than your voice. That gets you down to the posted background noise or Room Tone. Passes easily.”
Thanks so much!
- Stacy
When you get done reading a chapter or section, errors and all, File > Export > Export WAV (Microsoft) 16-bit as a perfect quality backup sound file so if something nasty happens, you won’t have to read it again. Make a copy of that on a thumb drive or some other safe place. Edit a copy.
[time passes]
After you get done cutting your chapter into shape and length (fluffs, duplications, spilled wine, tongue-ticks etc):
Select the whole chapter with the Select button on the left.
Effect > Notch Filter: 120Hz, Q3 > OK.
Then the three tools in the Audiobook Mastering Suite.
Then Noise Reduction. Select a tiny portion of noise-only (the two seconds before you start speaking) and Effect > Noise Reduction > Profile. This is where you tell Noise Reduction what to kill.
Then select the whole show with the Select button on the left.
Effect > Noise Reduction > 6, 6, 6 > OK.
Export WAV first. That’s your backup Edit Master if anything dreadful happens. Then export MP3 for audiobook submission.
This is where it goes off into extra chapters and considerations with types of MP3, how to write the sound file names, etc, but that should be one finished chapter.
You have two-fifths more work than you should because something in your studio is humming (Notch filter at the beginning) and I suspect we’re listening to your computer fan (Noise Reduction step at the end).
It’s possible your computer is causing both problems. Your computer is on shore power, right? Not batteries? Where is the power brick? I have a sound mixer power supply brick that hates microphones. MMMMMMMMMMM. Can you do a short test with the computer on batteries? Unplug the brick and put it in the next room.
Koz
If this was easy, anybody could do it.
Koz
If you get lost anywhere in there, post back.
Koz