Trying to meet ACX specifications

[kozikowski]

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Alice4raw11162018Patched.wav

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The catch is I had to design a custom filter to get rid of what I'm assuming is computer fan noise. You have a background hum or whirr at 81Hz musical pitch. It gets reduced in the Low Rolloff equalization step, but not enough to pass. 81Hz is not a regular hum sound such as 60Hz in the US and 50Hz in the UK. It's such an odd pitch that it almost has to be computer fan noise as computers don't have to follow the power system like an air conditioner or other room vent fans.

Even in the studio, can you tell if the computer is on just by listening?

You can do the rest of the work just by adding the custom filter before you apply Mastering 4. It shouldn't affect your voice.

Effect > Notch Filter > 81Hz, Q 6.

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Don't change the computer. If that's what it is, you are now married to that computer's fan noise.


So that's the technical considerations. That leaves theater. This is where I take one step back and you get to decide if you like the voice quality and everything about the sound. I think it's fine as it is, but there are very few voices where somebody can't find some way to change it. We should remember that your mastering process is already 25% longer than regular mastering (four steps instead of three) and you will need to remember to apply all the corrections to each chapter. Anything else you do is going to be in addition to all that.

Koz

[Trebor]

... Still doesn't pass ACX noise floor.
ChuckAlice4raw11162018.wav

There's a lot of infrasound in that , which no-one can hear but apparently is measured by the ACX tool.
If you remove those inaudible frequencies with this rumble-filter equalization, it passes ACX noise-floor test ...

100Hz rumble filter.png (23.06 KiB) Viewed 444 times

[chuckyocum]

WOW WOW WOW! Thanks again, Koz.

I'll definitely do the notch filter. But note that the computer is totally outside the whisper room, just leaving a solid-state keyboard inside on the table.

Chuck

[chuckyocum]

Thanks, Trebor. I'll try the 100Hz rumble filter, also.


Chuck

[kozikowski]

But note that the computer is totally outside the whisper room, just leaving a solid-state keyboard inside on the table.

How are you getting ventilation in the room? Mini whisper fans? Can you hear them change if you unplugged them?

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We had a conference room at work which was soundproofed. I sent a number of sound performances through that room. Yes, it had padded walls, etc, but it also had padded air ducts and I couldn't tell when the air conditioner went on.

If someone unplugged the computer with you in the room, could you hear it wind down? That whir tone behind your voice is coming from somewhere and it has all the signatures of a computer fan. If it walks like a duck.....


There is an insane test you can do with a long microphone cable. Look for the hum like that guy at the beach looking for Rolodex Watches in the sand with a metal detector.

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It's almost certainly a directional microphone so you aim it all over while wearing headphones and set Audacity for live monitor. The whir will get louder as you approach the noisemaker. That's how I found my music bass cabinet didn't go off when I turned it off and it sat there making a low volume hum that drove me nuts for a year.

Koz

[kozikowski]

Thanks, Trebor. I'll try the 100Hz rumble filter, also.

You should be careful with that. Audiobook Mastering 4 has a 100Hz rumble filter built in and you shouldn't apply both.

viewtopic.php?f=64&t=96103

Koz

[chuckyocum]

Hi koz,

Tried notch filter on my computer with Audacity 2.3.0 (see attached waveform). Failed ACX noise floor -55.5dB.
Fully mastered and Eq only pass (see attached) (-64.0 and 61.3, respectively).

Please listen to the audio. I'd love to know whether sound/theater quality of Eq only and fully mastered are OK. Also, could you suggest why my notch filter didn't pass? Also should I just master using Eq to minimize actions that might fail ACX sound/theater quality?

Thanks very much!


Chuck

Alice4raw11162018 mastered.wav

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Alice4raw11162018 eq only.wav

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Alice4raw11162018 notch.wav

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[DVDdoug]

Also, could you suggest why my notch filter didn't pass?

The notch filter should be used in addition to the other processing. I only notches-out 82Hz noise.

Also should I just master using Eq to minimize actions that might fail ACX sound/theater quality?

The default low-frequency roll-off is just to reduce low-frequency noise. And, since there is no deep bass in voice recordings the low-frequency roll-off doesn't affect the (good) sound.

Additional EQ can be used (sparingly) to as a corrective-effect to correct for microphone frequency response variations (i.e. if you microphone sounds "dull", etc.) or as an artistic or special-effect to slightly-change the character of your voice.

[Trebor]

.. I'd love to know whether sound/theater quality of Eq only and fully mastered are OK ...
Alice4raw11162018 mastered.wav

That does have a lot of mouth clicks. They can be reduced using a free plugin for Audacity called Paul-L's de-clicker ...

''Alice4raw11162018 mastered'' before-after click-reduction shown.flac

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this does not address all clicking problems: it only reduces the loudest high-pitched ones.

mouth-click reduction settings used.png (21.02 KiB) Viewed 345 times