How can I INCREASE noise floor for ACX?

This is my first recording of an audio book in my VO studio which is 110 square feet of soundproof space.

I spent A LOT of money to make sure that the space was as quiet as it could be… double drywall with Green Glue Noiseproofing Compound in-between and NO holes in the structure except a super quiet/ insulated baffled air exchange with the quietest of fans pushing the air through. All the electrical is scabbed onto the walls so there are no holes in the drywall and the door is closed using magnets to preserve it’s integrity…

There are large bass traps in all of the corners and the walls are treated with thick foam. There is a thick shag carpet on the floor and noise trapping products on the ceiling. The furniture and lamps have no hard surfaces and there are additional items in the room made of soft fabric to ensure that sounds won’t bounce off of hard surfaces.

The issue I am having now, is that it is TOO QUIET for ACX… is there any way of adding some noise floor in so that the files will pass their test?

Perhaps a file I could drop down on a separate track to get around this?

I have tried recording ambient room noise and adding it in but it doesn’t register.

Any suggestions welcome!!!

I would Generate some Brownian Noise in a separate track.

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Even if you have built a truly silent room,
there will always be some faint hiss noise generated by the electronics, (aka self-noise)

If your noise-floor is -∞ (minus infinity) then a real-time noise-gate “audio enhancement” is being applied, (not by Audacity).

e.g. software “Audio enhancements*” applied by your computer,
or hardware noise-gate in your audio-interface device.

[ * disable recording & playback enhancements for a faithful recording & playback ].

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I’m with Trebor. The reason ACX doesn’t like dead zero background noise is because it always means some processing has been applied and, as a rule, they hate processing.

Something in your audio chain is “helping you.”

Right. Because as you’re recording your “Room Tone” with its associated natural microphone noise in the -70dB to -80dB range, your mystery helper elf is back there somewhere in the electronics shoveling it out.

You can Generate > Noise as per Jademan above and add it to the recorded show, but that’s a desperation method and it makes my teeth hurt. That gives you the distortion of your audio chain processing plus noise.

Cool. Now what are you using for a microphone? Model names and part numbers are good. Do you like to use your computer for Skype, Zoom, Meetings or other communications jobs? It’s not unusual for their sound processing to stick around and affect everything you do.


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Congratulations!!! Noise is usually the biggest difference between a home studio and a pro studio.

I don’t know what the ACX minimum noise spec is and as far as I know, they don’t publish it. But I wouldn’t be surprised if you have some “artificially generated” digital silence somewhere in your recording. There is always SOME acoustic and electrical noise (not always audible) whereas in the digital domain you CAN literally have ZERO NOISE (minus infinity dB).

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They do. It’s -60dB.

I fuzzy recommend -65dB as a production goal to avoid surprises in the submission step.

That’s not to say you still can’t run into problems. There is a very common noise cause by USB connection damage. It sounds like “Baby Screaming On A Jet.” -60dB doesn’t work for that one and we have special filters for it.

ACX maintains a testing process called ACX Audiolab.

They test the same things that Audacity ACX-Check does, but they do not check noise.. Noise kills more people than almost anything else, so leaving that out was a mistake in my opinion.


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