Noise Compliance – (revision 1, minor updates 20171208)
We assume you’ve already been through AudioBook Mastering and failed ACX Technical Compliance because of noise (louder than -60dB) or your performance has odd background sounds you don’t like. Noise is common in a home studio.
— MICROPHONE HISS:
http://kozco.com/tech/audacity/clips/NoisyMicrophone.mp3
This is a gentle spring rain in the trees ffffffffff sound behind your voice. Microphone systems make noises like this naturally and it’s your job to make your voice loud enough so nobody notices the noise, but not so loud your voice distorts.
If the hiss isn’t too bad, try a gentle correction such as Noise Reduction of the Beast (6, 6, 6) or UNDO and try 9, 6, 6. You can hear the hiss getting quieter and recede into the background as you increase the first number: Nose Reduction. Try ACX-Check. If you need reduction as high as 12, 6, 6, your voice may get wine-glassy or honky and the show may not pass ACX human inspection.
http://manual.audacityteam.org/man/noise_reduction.html
The solution may be to change your announcing style or even the microphone. You should be about a shaka away from the microphone…
… or as close as a fist (louder and more intimate) but you may need a pop and blast filter.
— MACHINE NOISE:
Computer fan, air conditioning, refrigerators or other machines.
Turn off fans or machines while you’re presenting if you can. And yes, we understand the contradiction of needing to watch the Audacity screen, remove the noisy computer from your room and keep the computer one USB cable away from your USB microphone all at the same time. ACX did it by having an almost completely silent laptop in the studio to do the recording.
People have done it by extending the keyboard, mouse and monitor outside their studio, but you are warned against extending a USB cable, particularly with audio (or video) production.
Do not block computer vent holes.
If machine noises are constant and not seriously loud, they may respond to Effect > Noise Reduction.
Try a gentle correction such as Noise Reduction of the Beast (6, 6, 6) or UNDO and try 9, 6, 6. You can hear the hiss getting quieter and recede into the background as you increase the first number: Nose Reduction. Try ACX-Check. If you need reduction as high as 12, 6, 6, your voice may get wine-glassy or honky and the show may not pass ACX inspection.
http://manual.audacityteam.org/man/noise_reduction.html
— MOSQUITO WHINE:
Some computers and USB microphones hate each other and produce mosquito whine sound.
http://kozco.com/tech/audacity/clips/USBMicrophoneWhineClip.mp3
Whine doesn’t respond well to Effect > Noise Reduction.
Get and install Mosquito-Killer4.
https://forum.audacityteam.org/t/usb-whine-filtering-yeti-curse/45601/35
Effect > Mosquito-Killer4: …Mosquitoes to kill?: 8 > OK.
We expect the tool to make common USB whine vanish, but there are some versions of whine that don’t perfectly respond. Listen carefully and if Mosquito_Killer4 fails or doesn’t work enough, UNDO and post a help message on the Audacity Forum with a sample of the work.
https://forum.audacityteam.org/t/how-to-post-an-audio-sample/29851/1
I don’t know of any easy, foolproof way to permanently fix a USB microphone once you have the whine sound. The most likely fix is change the computer. You can do it by not using a USB microphone. You can use a very high quality analog microphone plugged into a stable USB interface.
— PERMANENT or IMPOSSIBLE NOISE:
There are no tools to remove noises that constantly change. If jets overhead, traffic noises, dogs barking and the TV next door are included in your show, they are now your permanent performance partners. Read the work again in a quieter room. Gating is very difficult to use and generally doesn’t help.
— COMBO PACK:
Nobody said you can’t have more than one noise. The ACX AudioBook noise test can be rough to pass with a home recording system. If you just can’t get there with the above tools, or you can’t get your voice to sound right, post to the Audacity Forum with a sound sample and send a clean, raw clip. Mention the three-digit Audacity number.
https://forum.audacityteam.org/t/how-to-post-an-audio-sample/29851/1
Raw, please. We can’t remove effects from a clip and posting your correction errors doesn’t tell us anything.
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